The first half of Straight Outta Compton is one of the best movies I’ve seen in a while. Tense, incendiary, tightly directed by F. Gary Gray (Law Abiding Citizen, The Italian Job) and beautifully acted by an ensemble cast fronted by Corey Hawkins (Non-Stop), Jason Mitchell (Contraband), and O’Shea Jackson, Jr. (Ice Cube’s actual son), Compton is fierce and unrelenting and explosive. …Until it downshifts about halfway through and becomes a chronicle of contract disputes, and then it loses all momentum and limps across the finish line, hobbled by a genre it outstripped within the first twenty minutes. It’s a worthwhile movie for a lot of reasons, and definitely worth seeing even if you don’t care about the history of rap, but the lame second half throws a big bucket of ice water over the fire and rage of the legitimately brilliant first half.

Written by Jonathan Herman and Andrea Berloff (World Trade Center), Compton begins in the 1980s as Dr. Dre (Hawkins), Ice Cube (Jackson), and Eazy-E (Mitchell) meet each other and begin making music together in Compton, California. Also along for the ride are DJ Yella (Neil Brown, Jr., Suits) and MC Ren (Aldis Hodge, Turn), but the focus of the movie is on Dre, Cube, and Eazy, just as they stand today as the most memorable members of N.W.A (the movie disposes of the rapper Arabian Prince entirely). The opening scene is exceptionally strong, as Eazy, then a drug dealer, flees from a police raid. Immediately the story of N.W.A. is positioned within the larger narrative of the war on drugs, and the outright hostile relationship between the police and the communities they’re meant to protect.

From this first scene all the way through the recreation of N.W.A.’s infamous performance at Joe Louis Arena in Detroit in 1989, when Cube—Jackson Jr. has perfectly captured, either by genetics or by a lifetime of watching his father, the real Ice Cube’s swagger and strut on a stage—defiantly and fiercely demands, “Yo Dre, I got something to say,” and launches into the scathing “Fuck tha Police” Compton is flat-out thrilling, a masterpiece of biographical cinema. The frustration is palpable, and the combination of stellar acting, Joseph Trapanese’s grinding score, Gray’s unflinching camerawork (aided by cinematographer Matthew Libatique), and tight editing from Billy Fox and Michael Tronick work to keep tension cranked all the way up.

The police are everywhere, a constant presence that descends at a moment’s notice to degrade and demean people who are otherwise just going about their business. And it’s impossible to miss how relevant this story remains today, as police brutality is once again a national story. “Fuck tha Police” is twenty-seven years old, but it could have been written today, and Compton is aware of that, as the film plays as a kind of echo-chamber, transcending mere biography and becoming a living record of the frustration, fear, and almost illogical hope that fueled N.W.A. and the community that spawned them. And had it ended there, with the Detroit performance of “Fuck tha Police” and N.W.A.’s subsequent arrest, carted off in cuffs but laughing, triumphant, Straight Outta Compton would have been extraordinary.

But it doesn’t end there. It keeps going for another hour, and the story shifts from the fire of discontent that propelled this group and gangsta rap into the national consciousness, to a by-the-numbers biopic tale of feuds and falling out. The stories represented in this portion of the film, as Jerry Heller (Paul Giamatti, recycling his Evil Music Manager schtick) comes to the fore and the group fractures over money disputes, have their own merit, but it’s simply not as interesting as the first half of the film. And even if you take the second half as a love letter to Eazy-E, who died in 1995 after being diagnosed with HIV, it still doesn’t measure up to the first half. Straight Outta Compton ends up an above-average biopic, but it could have been so much more.