Cassian is a genius at blowing things up. Primrose, an expert chef, knows all about mixing deadly surprises into scrumptious snacks. And Daisy, the eldest, has crafted nanny-hatinginto an art form.

It all begins when Papa Darling and his new wife leave them with Petronella Fryer—Nanny Pete—who, it turns out, is more of a thief than a nanny. This is fine with the children; they jump at the opportunity to put their ingenious nanny-defeating skills to use. Add in a hijacked Jaguar, a cruise ship full of burglars, and a very rare teddy bear, and the result is a caper of stupendously momentous proportions.