Agatha Christie's Partners in Crime

N Or M? Part 1

There's a leak on the Third Floor, and Tommy is the only man Major Carter can trust. Carter sends him on a mission so secret he can't even tell Tuppence: find a missing British scientist, a nuclear bomb, and a Soviet spy code-named N or is it M? Tommy goes in search of the kidnapper, but Tuppence is two steps ahead of him.