“Richard Donner,” reads the entry in legendary grump David Thomson’s Biographical Dictionary of Film, “has made several of the most successful and least interesting films of his age. And one doubts it’s over yet.” Rrrowr. (And this was before the release of Timeline, even.) As much as I generally admire Thomson’s grinchy tendencies, I find it hard to be too tough on the man behind such low-impact popcorn crack as The Omen, Superman: The Movie, and the first Lethal Weapon. He’s Hollywood, sure, with a resolute interest in staying between the studio-mandated lines—but there are worse crimes.

16 Blocks, Donner’s first film in three years, registers as a moderately intriguing attempt at reform: an initially spiffy exercise in gritty neo-noir finally torpedoed by the director’s lingering vanilla sensibilities and an intensely annoying central performance by Mos Def. Essentially a loose remake of Clint Eastwood’s The Gauntlet, scripter Richard Wenk’s quasi real-time premise finds a boozy, gimpy New York detective (Bruce Willis, underplaying nicely) charged with delivering a motor-mouthed convict (Mos Def) to the nearby courthouse in order to testify in a police corruption case. Several hundred gunshots later, it becomes apparent that his fellow cops have a somewhat vested interest in keeping the case unresolved. Donner’s no-nonsense, close-quartered approach to the material finds some genuine tension in the early stages, and allows for some ace byplay between Willis and chief pursuer David Morse throughout. Unfortunately, as matters progress, it becomes clear that the director doesn’t have his heart in following things through to their logically downbeat, fatalistic conclusion. By the time a major character lets slip his dream of opening a birthday cake business, the nervy, trust-no-one vibe is lost for good.

And then there’s the strange case of Mos Def, an actor who has generally made a habit of being the best thing about whatever he’s in (it’s early yet, but his sleepy, sorrowful detective in The Woodsman makes a strong bid for the cameo Parthenon of the decade, at least). Here, though, he adopts an inexplicable Adam Sandlerish baby talk so vibrationally offensive that I swore I could feel my rearmost fillings changing into lead. Whatever the initial motivation, Def’s performance runs dangerously close to nudging our sympathies toward the bad guys. Throw him to the wolves, blow him up, freeze him in liquid nitrogen, anything, just please stop him from talking.