Following a frenetic opening, Joe Carnahan's Detroit cop movie settles into an edgy two-hander as Jason Patric's alienated undercover man returns to the streets to investigate a cop killing with the dead officer's explosive partner, Ray Liotta. It skirts cliché, but it's powered by a redemptive, almost overwhelmingly emotional current; and it's a joy finally to see Liotta in a role worthy of his talents.