The head of Dartmouth Training College has been murdered, and his successor, Captain Hyde, suspects that he himself may have been the intended target. He enlists the help of his own son Philip, a reluctant cadet at the college, to help him confirm his suspicions about planned enemy action... but meanwhile, there is a Secret Service agent staying at the college observatory, the foreign-born professor of astronomy is behaving strangely, and Naval Intelligence disclaim any knowledge of what is going on...
Leslie Banks
as Capt. Hyde
Kay Walsh
as Alison Devar
Mackenzie Ward
as Newton Hulls
Cecil Parker
as Cmdr. Herbert
Simon Lack
as Philip Hyde
Ellen Pollock
as Margaret Hulls
Nigel Stock
as Rudd
Kynaston Reeves
as Prof Devar
Charles Eaton
as Commander-in-Chief
Ian Fleming
as Naval Intelligence Officer
Gordon Begg
as Waiter
Robert Field
as Insp. Blake
