Pretty Little Liars is still one of the guilty TV pleasures we love to keep talking about, even if it has left a gaping hole in our hearts.

Following four teenage friends -- Aria Montgomery (Lucy Hale), Spencer Hastings (Troian Bellisario), Emily Fields (Shay Mitchell), and Hanna Marin (Ashley Benson), who are still reeling one year after their friend and leader of their group, Alison DiLaurentis (Sasha Pieterse), has disappeared – the show, which ran for seven seasons, was seriously crazy.

Watch the girls trying to figure the identity of “A”, their nemeses who have been tormenting them and threatening to either ruin or end their lives, was pure gold. It was also pretty much devoid of anything supernatural (we all want to forget Ravenswood!) - just plenty of romance, secrets, murder, mistaken identities, face masks, black hoodies, red coats, elaborate life-sized dollhouses, and so much more.

But some of the insanity didn't always add up. If you didn't pay close attention (or possibly keep meticulous notes), you'd miss something. Either that, or you were left scratching your head and wondering what just happened?

Here are 17 Unresolved Mysteries And Plot Holes Pretty Little Liars Left Hanging.

17. THE MOMS AND THAT BASEMENT

This one still haunts many PLL fans. The Liars' mothers – Ashley, Veronica, Ella and Pam – get locked in Kenneth DiLaurentis' basement after spending a boozy night together trying to figure out if Kenneth killed his wife, Jessica. We never actually see them escape (and naturally they do), so what happened?

Cut to the final season, and the moms reunite, bringing up that time they got stuck in the basement. They stop short of giving us our answer, but show creator I. Marlene King later explained (sort of) on star Shay Mitchell's Instagram story. "Pam, who didn’t drink for a year, she had to take her clothes off, and they put oil all over her and they slid her out of the window." Hmm, that would have been fun to see.

Side question: Why did most of the Rosewood adults really suck at parenting?

16. WHO WAS THE “BEACH HOTTIE”?

This is another unsolved mystery fans love to bring up. Here's the deal: while vacationing in Cape May, Alison had a summer fling with a guy she called “beach hottie” in her diary. Apparently, she couldn't tell any of her friends about him because he'd “kill her.”

According to CeCe Drake's version of the events, the hookup resulted in a false pregnancy scare, and CeCe thought it was Detective Darren Wilden. Creator I. Marlene King once answered, "I thought that was Wilden. Wasn’t that Wilden? ... I’ve got to look it up, but I’ll get back to you on that."

Many die-hard Little Liars have also speculated it could have also been Ezra Fitz or Wren Kingston. But alas, nothing has ever been confirmed, so we'll just have to make up our own scenario on what went down.

15. WHERE DID CHARLOTTE GET HER ENDLESS CASH?

As we know, Charlotte DiLaurentis, aka CeCe Drake, was born Charles DiLaurentis and was Alison DiLaurentis' presumed dead adoptive brother/cousin who later transitioned into a woman. Charlotte is also revealed as the A-team leader in messing with the Pretty Little Liars.

One of Charlotte's methods of torture was an elaborate underground lair/dollhouse she built, in which each of the Liars' bedrooms were recreated. There were surveillance cameras everywhere (and a holographic TV) and Charlotte held them all hostage there.

How did Charlotte pay for the Dollhouse's hefty construction?

It was sort of explained that Charlotte had some kind of trust fund through the mysterious Carissimi Group, set up by Jessica DiLaurentis, but it was never made entirely clear why so much money was there or how Charlotte gained access it.

14. WHERE DID ARIA'S BROTHER MIKE GO?

Aria's little brother, Mike, was first introduced in the first season but then sort of fell off the map after season 2, only to appear again in season 5. He resurfaced as a total cutie who was dating Mona Vanderwaal. But when she faked her death, he tries to figure out from Mona's blood where she was (and then she ended up being held captive in a dollhouse).

Mike also ends up crossing paths with Charlotte, which is never a good thing.

Mike manages to survive that, but then once again disappears, never to return. It's true the actor playing Mike - Cody Christian - was cast on Teen Wolf in 2015, so clearly he went on to other things, but many fans felt like he should have at least made a cameo to see his sister, Aria, get married to Ezra in the last season.

13. WHY DID ROSEWOOD HIGH LET MONA RETURN?

Speaking of Mona, at the end of season 2, she was revealed to be the original A (listen, there are a lot of people who want to torment the Liars). Mona hated Alison for bullying her when they were in middle school, along with the other Liars because she's afraid they are going to take away her only friend, Hanna. (Which doesn't explain why she would torture Hanna too, right?)

After Alison disappears, Mona also assumes Ali's place as the mean queen.

When Mona is exposed as A after abducting and trying to kill Spencer , she enters the local – and very popular – Radley Sanitorium to get help, but then later is allowed to return to Rosewood High and interact with her victims to the point of harassing them again. Why, exactly?

It could have something to do with Mona hacking the school's computer and finding dirt on Vice Principal Tamborelli and then blackmailing him. But still, this girl shouldn't have been let back onto school property.

12. MAYA ST. GERMAIN'S DEATH

Maya's death really infuriated fans because not only did she have mad chemistry with girlfriend Emily, but she was also killed in season 2 by stalker, Lyndon James. Lyndon went around Rosewood pretending to be Maya's grieving cousin Nate St. Germain until he was uncovered as the murderer. Lame (and something King apparently later regretted).

One of the biggest puzzlers is the message Mona shares with the Liars about Maya.

Using a code Mona and Hanna once came up with, Mona started by reciting, “Miss Aria, you're a killer, not Ezra's wife," which is an acronym for “Maya knew.” Knew what, we all asked? But it turned out it was just that Maya knew her killer and had posted videos and blogs about it on her website.

But how did Mona know all that? Why does the code target Aria? It's just weird plot device.

11. TOBY'S BOOK OF POETRY FROM "SPENCER"

This is a tad convoluted. In a nutshell, in order to figure who the real Spencer is when standing in front of Spencer and her evil twin, Alex Drake, Toby Cavanaugh asks them both to name Spencer’s favorite poem in the book she gave to him. The real Spencer answers correctly, and boom! Toby has his true love back.

Except it was Alex, pretending to be Spencer, who gave Toby the book, so how could Spencer guess correctly? One Wikia fan said it was because even though Spencer never gave Toby the book, she had the same book in her possession and apparently Spoby had previously talked about their favorite poems together. Alex then bought the same book and gave it to Toby, but wouldn't have known about the favorite poem.

Maybe that makes sense, but the space for a plot hole is still pretty wide.

10. WHY DID SARA HARVEY WORK FOR A?

Sara, who was once the Queen Bee of her own high-school clique, looked a lot like Alison and became a giant red herring, so to speak, when she turned out to be Red Coat and Black Widow, as part of Charlotte's A-team in distracting the Liars.

How did Charlotte recruit Sara?

Alex revealed later that Sara was looking for “Charlotte’s greatest treasure” under the Radley, which we all assumed was money, but actually had to do with Charlotte's family. After Sara's whole involvement with Charlotte – from being apparently kidnapped and trapped in the Dollhouse, to seemingly using Emily but actually falling for her, to planting the bomb to blow up Radley but burning her hands instead – maybe Sara followed Charlotte's commands so she could eventually get her money. We'll never know for sure.

9. NOEL KAHN'S MOTIVE

Noel started out as just a regular guy, dating Aria, then Mona, then Jenna and then eventually helping Alison run away and stay hidden. Okay, he did that because Ali was blackmailing him (for pushing a girl down the stairs when he was drunk), but still. At this point, Noel didn't seem like the uber villain he would become.

Sure enough, Noel had been helping Charlotte all along - with the Dollhouse and everything - and wanted to kill the Liars, but he got decapitated instead.

It's just not made clear why he hates the Liars so much.

Alison did blackmail him at one point, but no other reason was revealed. He apparently had more motive in killing Shower Sara because Charlotte had left her money to fix her hands, and Jenna said Noel was strapped for cash when his parents cut him off.

8. HOW DID MONA GET MARY AND ALEX TO PARIS?

It's the end of the series, Alex's nefarious plan to take over Spencer's life by keeping Spencer (and Ezra) trapped in yet another constructed dollhouse, is foiled by Toby and the other Liars. Alex is seen being carted off by a policeman caught and the Liars can let out a collective sigh of relief.

But wait! The “policeman” was actually some French dude working for Mona, who has built her own dollhouse – in Paris, no less – and now has Alex and Alex's mother, Mary Drake, locked up and pretending to enjoy some tea. How the heck did that all happen?! Mona has been this brilliant all along, but it's a head scratcher on how she pulled this off.

Also, where is all this money coming from to all these dollhouses?

7. HOW DID ALEX KILL WREN?

Wren Kingston was definitely not a good guy so his death wasn't all that upsetting – but it would have been kind of awesome to see how Alex did it.

After going back and forth between Spencer and Melissa, Wren ended up totally falling for Spencer's evil twin and helped her masquerade as Spencer, even shooting her in the shoulder to match Spencer's scar.

Apparently, Wren got too close and couldn't see Alex as Spencer, so Alex killed Wren and made him into a necklace. You heard right. She turned his ashes into an diamond/eternity stone and wore it around her neck at all times, to keep him close.

Come on, they could have at least showed us how Alex made that happen. Big-time fail.

6. EDDIE LAMB'S CONNECTION TO ARIA

Another puzzler that keeps coming up when fans look back at the show is the fact Radley nurse Eddie Lamb somehow knows Aria. When she “volunteers” at Radley to try and get information about Bethany Young, Eddie meets her and says he thinks they've met before. How? Aria has never been admitted to Radley (one of the few who hasn't been), so how did Eddie recognize her?

Eddie Lamb is just one of many characters who show up for plot reasons and then disappear.

Some fans speculated at the time that maybe Aria had a twin sister, too, but of course that wasn't the case. Instead, we're just left with this still hanging in the air. Rght after that scene moment, Eddie is seen calling Ezra Fitz (who Eddie has met before) – then he disappears from the show for good.

5. TOBY'S MOM'S DEATH

Toby's mom, Marion, suffered from depression and was often institutionalized at Radley. It was originally stated that Marion killed herself, but in season 6, we find out Marion was thrown off the Radley roof by the disturbed 10-year-old Bethany Young. Bethany was up there hanging out with a young Charlotte DiLaurentis, but then she pinned Marion's death on her. Nice.

Yet, in season 4, Marion makes an appearance in a flashback when Toby and Alison are kissing as teenagers. If Charlotte, who is seven years older than Alison, saw Marion die when she was a kid, how could Marion be there when Toby is a teenager? He would have been an infant at the supposed time of Marion's demise.

So was that a ghost Marion with Toby in the flashback? It looks the season 6 writers missed the memo.

4. THE BARREL IN THE STORAGE

This still kind of bugs us. After Mona's “murder,” the Liars find a storage unit under Hanna's name that has some of Mona's things -- her phone, bloody clothes – and a large barrel big enough to stuff a body inside. The Liars believe Mona is probably in that barrel, but they never open it up to see who or what is inside or bring in the police. Because, you know, it's Pretty Little Liars and calling the cops is never an option, in case it incriminates someone.

Of course, we come to find out it can't be Mona because she wasn't actually murdered but kidnapped by Charlotte, so who exactly was in there? Marlene King did finally answer the question, telling Entertainment Weekly in 2015 that “Charlotte stole a cadaver from a medical school.”

Okay, but couldn't they have just revealed that on the show?

3. THE MANY PLOTHOLES INVOLVING CHARLOTTE

Charlotte, aka CeCe, is probably one of the most problematic characters on a show that featured multiple grown men in relationships with girls under 18. Some of them we have already mentioned, but there are many more.

How did Charlotte get away with pretending to be Alison at Radley when she'd already been there for ages? Didn't they know what she looked like?

How could CeCe be the prom queen at Rosewood High when she never went there?

What was up with CeCe's roomate at UPenn when CeCe was supposed to be at Radley? Also, how could CeCe spend so much time with the DiLaurentises in Cape May when she was supposed to be in Radley?

There are too many plot holes to count, and none of them ever really explained.

2. CHARLOTTE AND ALEX'S "FAMILY" OBSESSION

An important question: why did tCharlotte and Alex hate the Liars so much when all they wanted was to be part of a family? When Alex and Charlotte reconnect in London, it's great for them. Along with Wren and Archer, the girls were happy and finally felt like they had a family. But then Charlotte blows it by going back to Rosewood because she missed the “game” of torturing the Liars – and is killed by Mona.

Alex becomes A.D. to avenge her sister's death and then becomes super jealous of Spencer and her life with her gal pals. We get it, but is that really enough to make her go completely crazy and try to kill all of the Liars? It just seems to have defeated the purpose.

1. WHY WERE OUR PRETTY LITTLE LIARS TORTURED SO MUCH?

Is it really just because they were friends with Alison, whose basic crime was being a bully in middle and high school and sleeping with a lot of guys?

The whole premise of the show revolved around all these secrets the Liars were holding on to, but really, before Alison disappears, it seems the girls were just living their teenage lives. Sure, some of them came from messed up families, had other friends and boyfriends who were pretty messed up, but the Liars – Hanna, Aria, Spencer and Emily – didn't seem all that sneaky and nefarious in their own right.

In fact, they definitely got the short end of the stick. Many people hated Alison for all her shenanigans, but that's not entirely fair it rubs off on her supposed best friends. But hey, they find closure in the end, so it's all good.

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We know there are way more Pretty Little Liars puzzlers. Let us know some of your unresolved questions in the comments below!