In the film's gripping opening, Agent Eric Olsen, portrayed by Lonnie Farmer, is seen interrogating Kevin Weeks, played by Jesse Plemons. Agent Olsen seeks information about Weeks's past connections with the Winter Hill Gang in South Boston, as well as insights into the dealings of former FBI Agent John Connolly, represented by Joel Edgerton, and the notorious fugitive, James "Whitey" Bulger, brought to life by Johnny Depp.
The narrative flashes back to Boston, 1975, where Kevin finds himself working as a bouncer outside a bar often frequented by Whitey, who is known to his close ones as Jimmy. Here, we witness Whitey’s ruthless demeanor, as he expresses his disdain towards John Martorano for his unsophisticated behavior while snacking. Tensions rise when Kevin gets into a scuffle with a man revealed to be Whitey’s cousin, prompting Whitey to step in.
In a further display of brutality, Whitey coerces Kevin into driving him and a member of the Angiulo crime family to a secluded beach where they violently assault the man, leaving him for dead. Despite this, Olsen learns from Kevin that Whitey was a well-liked figure in their neighborhood. The film reveals Whitey’s complicated family dynamics as he visits his mother, played by Mary Klug, where they engage in their favorite card game, Gin Rummy, while his brother Billy, brilliantly portrayed by Benedict Cumberbatch, a state senator, joins them for dinner.
The tension escalates with John Connolly’s return to Boston; a former acquaintance of Whitey and Billy, he approaches Billy intent on forming a connection with Whitey. John proposes that Whitey acts as an informant, leveraging his position to dismantle rival gangs, specifically targeting the Angiulos. After some hesitation, Whitey ultimately agrees to this dangerous alliance, seeing it as a chance to eliminate his enemies.
As the plot thickens, a violent confrontation arises when the Angiulos murder a member of the Winter Hill Gang, propelling Whitey to fully commit to his role as an informant. John shares his plans with his superior, Charles McGuire (played by Kevin Bacon), and his colleague, Robert Fitzpatrick, portrayed by Adam Scott, although skepticism looms over the mission's success.
In a scene highlighting Whitey’s volatile relationships, he confronts Tommy King after a police altercation, warning him to temper his aggressive attitude. Whitey also balances his life outside of crime with visits to his girlfriend Lindsey Cyr, played by Dakota Johnson, and their son Douglas. During one poignant dinner, Whitey expresses a misplaced pride in Douglas's behavior at school, subtly teaching him questionable morals about confronting conflict.
Despite John’s warnings to refrain from significant criminal activities while he acts as an informant, Whitey disregards this and executes Tommy. This chilling event occurs alongside a haunting flashback where Whitey grapples with the illness of his son, resulting in emotional clashes with Lindsey over the medical decisions that follow.
By 1981, the power dynamics shift dramatically as Whitey has fully taken control of the Winter Hill Gang. While he offers crucial intelligence to John about the Angiulos, his own morality faces dire tests when he removes obstacles in his path through violent means. Amid this turmoil, they continue to bond, much to his wife Marianne’s discontent.
The plot explores Whitey's cold calculus as he orchestrates various murders and maneuvers politically as law enforcement begins to close in on their operations. The gripping conclusion comes as the law finally catches up with the gang members and John Connolly himself is ensnared in the web of deception woven by his choices.
The film leaves us with a stark reminder of the consequences of their choices, as text reveals where characters like Kevin Weeks and John Martorano ended up, juxtaposed against the severe punishments faced by others like Stephen Flemmi, who serves a life sentence. The final scenes shift to 2011, showcasing an older Whitey’s arrest after evading capture for 16 years, culminating in a sobering portrayal of his notoriety and the justice ultimately served.
