What is the true purpose of the Heavy Water machine, and why does the answer lie inside the Brooklyn Bridge?

Charley encounters the seedier side of mob life while the Doctor and Glory Bee get closer to locating her missing relative.

New York, 1938. Orson Welles prepares to make an historic broadcast from the studios of CBS and there's a new gumshoe in town.

The Martians are coming. Or are they? With time running out, the Doctor is forced to play a desperate bluff against the aliens.