Melissa McCarthy shines in this clever action-comedy showcase provided by the writer and director Paul Feig, but the movie's tightly contrived plot and uniformly positive emotions constrain her comic genius.

Hollywood is gradually figuring out what to do with Melissa McCarthy.

McCarthy has much more to discover about herself as an actor and an avatar and a cultural signifier, and I hope she doesn't get trapped by one role, one genre or one franchise. But her campaign of conquest is going well.

What does work, in every scene, is Melissa McCarthy's performance. She's as funny and as winning as anyone in the movies these days.

Feig's cheerfully feminist script makes only as much sense as it absolutely must, while providing McCarthy with chances to crack wise, show vulnerability and class, and do some of the more elegant pratfalls you'll have seen in a while.