[WARNING: This article contains SPOILERS for The Flash Season 2, Episode 22.]

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With only one episode left until the guaranteed-to-be-shocking season finale of The Flash, one might expect some high-energy, action-packed spectacle with a killer twist ending. But The Flash is known for its quieter, more heartfelt moments, and combining that formula with Barry's newfound perspective on life and heroism (granted by his journey into the Speed Force), the penultimate episode of the show's second season takes its time. Which means the heartbreaking conclusion packs even more punch.

In "Invincible", directed by Jesse Warn with story by Greg Berlanti & Andrew Kreisberg, and teleplay by Brooke Roberts & David Kob, Barry (Grant Gustin) tackles the metahuman army unleashed by Zoom with newfound confidence - which has his friends worried. But as Zoom's (Teddy Sears) mystery plan takes shape in the shadows, the speedster villain decides he has to put Barry through the same loss and heartbreak he did, by taking the one person he most cares for.

The Siren's Call

Before getting to the most tragic part of the episode (the last moments), we have to point out that the colorful characters of the 'Metapocalypse' actually resulted in little screen time, with Barry dispatching dozens in a matter of seconds. Thankfully, one metahuman stood out, thanks to the recasting of Arrow regular Laurel Lance (Katie Cassidy) as the villainous Black Siren. Although her dialogue still suffered from the heightened, often cheesy one-liners that CW villains seems doomed to speak ("Bye, bye, birdie"), Cassidy brought new weight to her persona, not to mention the fan service itself.

Surprisingly, it wasn't the destruction of multiple buildings, or bursting of Barry's ear drums that made her presence memorable, but the comedy. First off, seeing Wally's vehicular rescue send her flying to the pavement is almost guaranteed to bring some chuckles in an otherwise serious episode, but the "worst plan ever" concocted by Cisco (Carlos Valdes) giving he and Caitlin (Danielle Panabaker) a chance to shine.

Cooking up the wardrobes of their doppelgangers with speed that would make any cosplayer blush, the Cisco/Caitlin/Reverb/Killer Frost scenes are a fitting reminder of how drama, suspense, and goodhearted comedy form the DNA of The Flash. The scene is cut short when Siren exposes the ruse, but considering what's coming, the break from the doom and gloom of previous Zoom-centric episodes - or Barry's surreal sojourn into the Speed Force in the week previous - is more than welcome.

Even if it comes at the price of seeing Barry actually have to deal with his main weakness, pointed out by Zoom. In short: that he can never keep his eye on the goal if the safety of everyone around him is his top priority.

Another Heartbreak

Just when Barry seemed most optimistic, and seemed to recognize that his team had managed to defeat every villain thrown their way, fate reared its ugly head to show him that Zoom wasn't like any villain he had faced before. The final moments are shocking, but with Henry Allen having returned as mysteriously as he exited the series previously, the writing was on the wall.  And although the writers took pains to plant seeds of doubt along the way - that fear is good, and false confidence can get Barry or those close to him hurt - it's a shame that such foreshadowing hit some dull notes along the way.

It's Iris (Candice Patton) who best voices the idea, explaining that a little fear can keep a hero alive - but it can't make up for the numerous times in the episode that Barry's peaceful, optimistic, trusting demeanor and faith that good would prevail (when it actually is so far) is met only with concern and suspicion by his family. Since the audience is, presumably, happy to see Barry briefly... happy, the tone of his friends' concern is often confusing. But mainly, it foreshadows doom more explicitly than was really needed: the final scene of family gathered together toasting their fortunes did the trick all by itself.

The episode has planted many seeds, from Wally realizing Barry's identity, to Cisco exhibiting new powers, but it's the murder of Henry Allen (John Wesley Shipp) that will be most remembered. From Hunter's crazed promise to show Barry the truth, to Henry's final words of live and pride, the editing, performances, and cliffhanger ending succeed in making this as harrowing an experience for the viewer as it is for Barry. And with just one episode left to go in the show's second season, fans will be tuning in with absolutely no idea what happens next.

We'd say that's a unique achievement in TV adventures, but at this point, it's practically The Flash's trademark.

The Flash continues with its season finale "The Race of His Life" next Tuesday @8pm on The CW. Watch a preview below: