Four inmates of the Central Park Zoo—a lion, a zebra, a hippo and a giraffe (voiced by Ben Stiller, Chris Rock, Jada Pinkett Smith and David Schwimmer, respectively)—escape from their cages and wind up on the island of Madagascar, where they are befriended by a tribe of lemurs. DreamWorks’ latest animated feature, written by Mark Burton and Billy Frolick and directed by Eric Darnell and Tom McGrath, is a wacky parade of verbal and visual gags, but it never coalesces into a real story—it has ingenuity without inspiration. Did McGrath and Darnell, et al., recruit their celebrity voices and then try to build a story around them? (The actors are star-billed as if they actually appear rather than just contribute voices!) If so, the filmmakers got it backward; they should have developed characters and then found the right voices.