When a cop at a crime scene needs someone to stay with the bodies until the detectives arrive, he asks “who don’t we need?” That would be tired, slow, Jack Mosley (Bruce Willis). As soon as the other cops leave, he limps into the kitchen and takes a bottle of booze out of the cabinet, then sits on the sofa, pours himself a drink, and waits until he can go.

Back at the station, he is about to sign out for the day when his lieutenant assigns him one more job. A prisoner has to testify before a grand jury 16 blocks away before 10:00, and it is now Jack’s responsibilty to deliver him.

So Jack puts Eddie (Mos Def) in the back of a squad car. On the way to the courthouse, he stops at a liquor store, leaving Eddie in the car. Two men try to kill Eddie.

It turns out that a lot of people will do everything they can to keep Eddie from testifying. And that powerful people were counting on Jack to “do what he always does.” Does that mean “mess up” or “go along?”

This movie is 2/3 video game, as Jack and Eddie find dangerous surprises around every corner and in a variety of settings, including the obligatory Chinatown scene. Bang, duck, bang, duck, bang, shoot back. But the other third makes it work — that’s the sure direction of a well-constructed script by Richard Donner, balancing tension, thrills, and a few well-placed laughs, with sharp, clever performances by Willis, Def, and David Morse as Jack’s former partner.

Willis is always underestimated as an actor. It’s easy to do because he never seems to be trying very hard. But that just shows how good he is. In the middle of an action movie he gives a subtle, complex, and nimble performance that increases the tension, never distracting from it. Mos Def gives depth and appeal to a character who has two functions in the script: contrast with Jack’s burn-out and McGuffin prop to be shot at and fought over. Eddie’s non-stop commentary could have quickly become annoying with a less skillful performer. But Def makes the rhythms of Eddie’s speech a counterpoint to the script’s ticking clock. The moment when he has to make a big decision is beautifully played. This 16 block journey is one audiences will enjoy being along for the ride.

Parents should know that this movie has non-stop action and peril with many tense situations and a lot of violence (mostly shooting). Many characters are injured and some are killed. A character abuses alcohol. Characters use brief strong language and there are some mild sexual references.

Families who see this movie should talk about whether and when people can change. Why did Jack decide to protect Eddie? Why did Eddie decide to help Jack? Why is Eddie’s riddle important?

Families who enjoy this movie will also enjoy the best in this genre, Midnight Run (non-stop very strong language), Speed, and Willis’ Die Hard 3.