A harmless recombination of mice detectives, missing cheese, and the inevitable French connection. Called in when a valuable 500-year-old cheese disappears from a locked room in the mansion of J. P. Cadwalader, Detective Tweedy and his assistant Rollo discover crumbs and a brie label at the scene. . . and so it's off to the district of Brie in France, traveling in J.P.'s submarine and swimming the last stretch when a swordfish saws through the sub. In Paris, cheese museum curator Monsieur Chandelier pronounces the crumbs too young to be from the missing cheese--and then it's back home by seaplane to find the culprit and the cheese inside a column in the locked room. But the ""thief,"" a fellow connoisseur who's been subsisting on J.P.'s brie while in hiding, was only looking at the Great Cheese: ""I was only imagining how wonderful such a cheese would taste."" Whereupon J.P. decides that ""cheeses are to be eaten"" and sits down with Tweedy, Rollo, and the thief to Share the pleasure. Active, but not especially sharp.