Mark Wahlberg's new movie Spenser Confidential has released on Netflix, based on the popular book series by Robert B' Parker — how does the Netflix Original film compare to its source material? In addition to Spenser Confidential disappointing critics, some fans of the long-running book series may cry foul at the film's adaptation; is it faithful to its original incarnation?

The Spenser novels — of which there are over  40 — follow the titular character, a Boston-based private investigator (formerly a state policeman, boxer and Korean War vet). When Robert B. Parker sadly passed away in 2010, his estate selected author Ace Atkins to take over the series. In 2013 he wrote and published Robert B. Parker's Wonderland, a Spenser novel, the storyline for which was loosely used to fuel Peter Berg's poorly-reviewed Netflix adaptation Spenser Confidential. 

Related: Is Spenser Confidential Based On A True Story? Influences Explained

Whilst there are enough similarities for Mark Wahlberg and company to retain the film's title of Spenser Confidential, there are a number of deviations from the source material; be it the characters' behavior or the events of the novel, Robert B. Parker's Wonderland.

Mark Wahlberg Playing Spenser

Spenser Confidential Wonderland

Mark Wahlberg's version of Spenser tends to feel more like Mark Wahlberg playing Mark Wahlberg rather than anything else. Spenser of the source material is of course a fairly standard big, tough guy (as many fictional PIs are wont to be); yet, what has him stand out from the crowd is his intelligence. Robert B. Parker's Spenser was fond of quoting lofty literary influences like Shakespeare, apparently for his own entertainment. Viewers don't see any similar such tic from Wahlberg on screen in Spenser Confidential.

There are elements to the Spenser character that Mark Wahlberg finds accuracy in; for example, Spenser's assertion of doing the right thing, no matter whether it be legal or not. As he says to the grieving widow Letitia (Hope Olaide Wilson), the reason for helping her is because it's "the right thing to do". Spenser's proclivity for getting beaten up, or being unlucky in Spenser Confidential's many fight scenes, is as present in the movie as it is in the novels.

Spenser's Ally Hawk

Winston Duke and Mark Wahlberg in Spenser Confidential

As Winston Duke's star grows, following breakout appearances in Black Panther and UsSpenser Confidential feels like the next stepping stone in elevating the charismatic actor to star status. Duke appears in Spenser Confidential as the PI's newfound roommate Hawk — Spenser's longtime ally and best friend from the Spenser novels.

Related: Every Song on Spenser Confidential's Soundtrack

Hawk's appearance in Spenser Confidential is a drastic departure from the source material, as Hawk doesn't actually appear in Robert B. Parker's Wonderland, upon which this movie is based. Instead, Spenser enlists the help of recently-acquired mentee (and awesomely-named) Zebulon Sixkill. In the Spenser novels, Hawk shows up as a highly capable, extremely dangerous enforcer and occasional hitman; initially, an opponent to Spenser — although they eventually become inseparable best friends.

In Netflix's Spenser Confidential, Hawk's role seems to have been combined with Sixkill's from the Wonderland novel. Sixkill is a raw talent who is taken under Spenser's wing, the now-grizzled PI looking for an apprentice for which to impart his skills and wisdom. This jibes with Hawk's appearance in Spenser Confidential, where he's presented as an amateur MMA fighter who still doesn't quite know how to land a punch. According to Duke, Hawk has been updated to reflect the modernization of Boston itself. The result is a very fun performance that might not feel enough like Hawk for longtime fans.

Spenser's Love Interest Cissy

Mark Wahlberg and Iliza Shlesinger in Spenser Confidential

Iliza Shlesinger plays Cissy, Spenser's love interest in Spenser Confidential. Portrayed as feisty, dynamic, smart and sexy, she's one of the more entertaining parts of the movie, not taking any guff from anybody — not Spenser, not Henry and certainly not the bad guys. There is no Cissy in the Robert B. Parker Spenser novels; rather, the object of Spenser's affections throughout the majority of the books he appears in is his one true love, Susan Silverman.

Related: The Witcher: How Netflix's Bathtub Scenes Are Different From The Game

Silverman's fiercely independent, and a good sounding board for Spenser's many trials and tribulations, but that is pretty much where the similarities with Cissy in Spenser Confidential end. Susan is a psychologist; Cissy adopts dogs. Susan is pretentious; Cissy is a little rough around the edges. It's also fairly unlikely that Robert B. Parker envisioned Susan's voice as being based off of Peter Griffin's — Shlesinger's inspiration for the role.

Spenser Confidential and Robert B. Parker's Wonderland Plot Differences

Spenser Confidential Wonderland

The main differences between Spenser Confidential and Robert B. Parker's Wonderland stem from the plot. Whilst the finale at the Wonderland race track is present in both book and film, the steps taken to reach it are wildly different. In the novel, it's Spenser's longtime friend and boxing coach Henry Cimoli — played in Spenser Confidential by Alan Arkin — who comes to the PI for help. Henry lives in an apartment complex near Wonderland, and when he refuses to sell to the mysterious buyers of the race track, thugs are sent after him to apply some pressure. Spenser takes Sixkill with him to deal with the thugs, which they do fairly easily, before going and arranging a better deal with the land developers on behalf of Henry and the other tenants. Things end up going to hell, naturally, leading to our heroes fighting for their lives.

This all varies differently from the plot of Spenser Confidential, where the story sees Spenser just getting out of prison and immediately being eyed for the murder of his old, corrupt police captain. Investigating the murder of Captain Boylan and another officer named Terrence Graham, who dies in a suspicious suicide, Spenser stumbles upon a wider conspiracy relating to an unsolved murder from five years prior. The murder of Boylan and Graham leads Spenser to discover that his old partner Driscoll (Bokeem Woodbine, last seen in Queen & Slim) is part of a conspiracy attempting to turn Wonderland into a casino; a crime ring that includes corrupt cops, ruthless drug lords, and one hapless Irish mob enforcer by the name of Tracksuit Charlie. When Driscoll abducts Henry, Spenser and Hawk arrive to save the day and take down the assembled bad guys at Wonderland.

Spenser Confidential works as an origin story for Spenser; he goes from his prison stint to dreaming of life as a truck driver in Arizona to a new calling as a PI who helps those in need on the streets of Boston, alongside newfound ally Hawk. In the Wonderland novel, Spenser has already been a PI for years and has been working with Hawk for almost as long. Essentially, Spenser has been given a new on-screen origin story with the backbone of the Wonderland novel as a building block and backdrop.

Next: What To Expect From Spenser Confidential 2