Based on Randall Sullivan’s 2002 tome “LAbyrinth: A Detective Investigates the Murders of Tupac Shakur and Notorious B.I.G., the Implication of Death Row Records’ Suge Knight, and the Origins of the Los Angeles Police Scandal,” Furman’s movie tells the story of, um, all of that. Not since “The Assassination of Jesse James by the Coward Robert Ford” has a title saved film critics from so much tedious plot summary. Depp plays a real guy by the name of Russell Poole, and he plays him twice over across parallel timelines: One in 1997 when Poole is an oblivious gumshoe who sticks his nose into something that’s stink covers the entire LAPD, and one almost 20 years later when he’s an unemployed Miss Havisham in his late 50s who cosplays as a detective (complete with serial killer stringboards wallpapering his musty apartment) because he’s still haunted by the case that ruined his life.

In theory, the temporal pincer attack of Christian Contreras’ script might have contrasted the naivete of a young man who trusted that the LAPD had cleaned up its act after the riots in ’92, with the jaded obsession of an older man who tumbled down the rabbit-hole for so long that he’s lucky to have emerged with a pulse — if not a pension. In practice, “City of Lies” is so understandably overwhelmed by the sprawling mystery at its core that it never figures out what to ask of either history or itself. Or how. The central questions that drive this movie are “who killed The Notorious B.I.G.?,” “why?,” and “is it really possible that one of the most infamously corrupt police departments in American history was… corrupt?” The problem is that older Poole is the first person on Earth to “figure out” the answers to the first two — Sullivan’s book, based on Poole’s testimony, controversially asserted that Suge Knight paid some dirty cops to pull the trigger in retaliation for Tupac’s murder — and the last person on Earth to solve the third. Poole’s journey into the bowels of the LAPD starts on the day of B.I.G.’s funeral, when an unrelated road rage incident ends with an undercover white cop (Shea Whigham) killing the off-duty Black cop (Amin Joseph as Kevin Gaines) who pulled a gun on him at a traffic stop. The details of what happened aren’t in dispute — there’s hard evidence proving that Gaines was following a pattern of aggressive behavior — but the department is still reeling from the one-two punch of the Rodney King attack and the O.J. trial, and accurately identifies this as a media shitstorm in the making. Brought in to ask questions (but not too many), the guileless Poole soon discovers that Gaines’ car is registered to Death Row Records, and like a dog with a bone he starts digging at the dirt even when the chief of police makes it clear that he just wants this whole thing to go away.

 Meanwhile, in the 21st century, a muckraker with his own Biggie-related demons to exorcise is trying to lure the deadbeat Poole out from the musty crypt of his own failure (Forest Whitaker plays a fictional journalist named Jack Jackson, presumably because “Generic McPlotDevice sounded too Irish for a Black character). Whitaker remains one of the most compelling people at whom a camera has ever been pointed, and Furman understands the actor is never more watchable than when playing a role that destabilizes his nature gravitas with an uneasy sense of desperation. Jack Jackson might only exist to goad Poole back out into the world and prove that the LAPD is still racist (say it ain’t so), but there’s some fun in watching him square up against an uncharacteristically humbled Depp. The disgraced artist formerly known as Grindelwald is also mesmerising in his way, as the most consistent source of tension in “City of Lies” comes from Depp trying to play someone who a producer on the film has described as “a cliché of normal.” That’s not exactly the vibe we get here — handcuffed by the source material’s lovingly sanctimonious take on Poole, Depp comes off as a crackpot shut-in who struggles to reconcile his moral philosophy with the reality of how people behave in the wild — but there’s a fish-wearing-pants fascination to watching him embody the only sane man in a world gone mad. It’s one of the few post-Jack Sparrow performances that makes you mourn what the back nine of Depp’s career might have given us if not for his method-worthy commitment to public disgrace. And while the faded star is now old enough that he needs to be aged down for the flashbacks instead of aged up for the “present day” scenes, Depp is believable in both timelines; his ’90s scenes opposite Poole’s ultra-pragmatic partner (an excellent Toby Huss) are almost rich enough to forget who you’re watching. And if “City of Lies” had focused exclusively on Poole’s role in the leadup to the Rampart scandal — which the film, in its most Oliver Stone-like moonshot, frames as an $125 million smokescreen to obscure a lawsuit for B.I.G.’s future earnings potential that would have supposedly bankrupted the city of Los Angeles — perhaps it might have worked as a story about a man’s loss of innocence in the face of a rot too deep to be reformed. On the other hand, that approach would have meant losing the film’s most powerful scene, in which Voletta Wallace (playing herself) meets Jack in a diner and returns us to the human cost at the center of this corrupted maze. It also would have demanded that “City of Lies” focus less on what the public doesn’t know about this case than on the more relevant question of why those details have been swept under the rug, and Furman’s movie lacks the craft or the confidence to address the unresolved questions of institutional cancer.

It’s implicitly understood that a movie directed by the guy who made “Runner Runner” isn’t going to solve a murder that’s hovered over modern American history for more than 20 years — that’s what HBO’s Sunday night lineup is for. But unlike David Fincher’s “Zodiac,” which is far and away the most obvious point of comparison, “City of Lies” doesn’t accept the mystery. It only feigns interest in becoming a human drama about the price of obsession so that it can sink its teeth into all the usual grassy knoll details about Wallace’s killing and the men who supposedly did it. There’s something admirable about Furman’s attempt to salvage Poole from the swamp he drowned in, but “City of Lies” is told with a simplicity that leaves this story feeling less like an inescapable LAbyrinth than it does the kind of maze that you might find on a diner placemat.

Grade: C-

“City of Lies” is in theaters now. As new movies open in theaters during the COVID-19 pandemic, IndieWire will continue to review them whenever possible. We encourage readers to follow the safety precautions provided by CDC and health authorities. Additionally, our coverage will provide alternative viewing options whenever they are available. Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.