Ready to head down the rabbit hole of the unsolved murders of Notorious B.I.G. and Tupac Shakur? Well, so am I.

Let the author of a book that investigated the crime,”LAbyrinth,” and the director of “The Lincoln Lawyer” take us into a “J.F.K./Kill the Messenger” deep dive into these cases and “theories” on what happened, and who caused it.

They were wildly famous people murdered in front of witnesses in two jurisdictions with a big LAPD connection to them both, especially the killing of Christopher “Biggie” Wallace in downtown Los Angeles in 1997.

“City of Lies” is another lone-investigator-pursues-a-truth-others-don’t-want-to-see narrative, this one built around an LAPD detective, Randall Poole (Johnny Depp) and a reporter, Jack Jackson (Forest Whitaker) digging into this “cold case” decades after the killings went down. Jackson is based on investigative reporter Randall Sullivan, who collaborated with Poole in writing “LAbyrinthe.”

Director Brad Furman starts with a peripheral crime set-up to make us believe one thing, but which unravels the larger tale as we see it from another angle. That’s kind of how the entire film plays as well, a lot of info, some of it misdirecting our attention.

He lets his film debunk the “Biggie put out a hit on Tupac” myth — again — and concentrates on the killing of Christopher Wallace.

We see the crime scene modeled in Matchbox cars and meet the faces of the the byzantine world of off-duty cops aligned with Death Row Records or entangled in the Rampart corruption (and worse) scandal.

Here it is, 24 years later, and we don’t know why this case/these cases were never solved, don’t know whether Los Angeles police officers are implicated and hear only “I can’t comment on an open investigation” from that circle-the-wagons department, a dodge even Joseph Heller (“Catch-22”) would admire.

But as the film carries out a public service, renewing interest in shamefully unsolved crimes, as we hear the mantra “A detective says ‘I don’t know until I can prove it,'” and as the cast of characters grows even as interest in the case wanes, “City of Lies” loses its way as only a story without a satisfactory ending can.

An opening road rage incident seems to point to an armed, undercover cop (Shea Whigham in full redneck mode) gunning down a fellow officer (Amin Joseph), also undercover, and uses his “team” to cover up the crime.

But Officer Gaines (Joseph) was notorious in his own right, and driving a vehicle connected to Suge Knight’s record-label-as-street-gang, Death Row.

And that’s how Det. Poole gets sucked into “the labyrinth,” asking questions, collating stories, stumbling into this or that “undercover” law enforcement officer doing this, or that “off-duty” cop up to no good in some other regard.

Whitaker’s reporter shows up 18 years after the crime to badger the now-retired and reluctant Poole into downloading everything he learned in the case, which points us away from the “record label beef” that was quickly attached to the murders, and towards renegade police, Fruit of Islam “security” folk, Suge Knight and the uncomfortable post-OJ/post-Rodney King LAPD facing the spectacle of “white cops accusing Black cops” in two high profile murders.

The performances are solid, and the early scenes — recreating the crimes, etc. — are fascinating at a documentary level. Setting up the context is useful, a PD under a cloud and determined to avoid race riots that might return if dirty cops were in on all this.

But the rabbit hole closed in for me about an hour in. One too many “informants,” two or three too many police (Michael Pare and Toby Huss are cast as a couple of them), the bizarre media entity that this Jack Jackson is allegedly reporting for make the movie a spider’s web of competing, confusing threads.

And Depp’s “I’m obsessed with the truth” crusading detective, disillusioned with the idea of righteous “brother officers,” takes on a whiff of prosecutor Jim Garrison’s deluded, self-righteous crusade at finding the “conspiracy” that murdered Kennedy in “J.F.K.”

Yes, we can believe Poole’s “The only cases like this (high profile) that aren’t solved is because the police don’t want” to look, or have others look, at that solution. You don’t have to be downwind to think this whole affair smells to high heaven.

But you can’t just throw a lot of characters and facts and suspicious connections and theories at the viewer and have us made sense of it for you.

MPA Rating: R for language throughout, some violence and drug use 

Cast: Johnny Deppy, Forest Whitaker, Shea Whigham, Xander Berkeley, Michael Pare, Toby Huss

Credits: Directed by Brad Furman, script by Christian Contreras, based on a book by Randall Sullivan. A Saban Films release.

Running time: 1:52