- Michael Kingston, a.k.a. Bill Saunders, a.k.a Dirk Brandt
- Diane, his wife
- Tommy Hambledon, a.k.a. Hendrik Brandt
- Dixon Ogilvie, Michael's school chum
- Professor Amtenbrink, retired German scientist
- Max von Bodenheim, German Intelligence
- Charles Denton, a.k.a. Ludwig Wolff
- Kaspar Bluehm, a German
- Marie Bluehm, his sister
Synopsis: Michael Kingston, underage, assumes the fake identity of Bill Saunders in order to join the British military. He is seen as a good prospect for intelligence work, and comes under the wing of Tommy Hambledon.
They team up, assuming the identities of Hendrik Brandt and his nephew Dirk. As Dirk Brandt, he infiltrates German intelligence, cultivating a friendship with Max von Bodenheim.
First they investigate whether retired professor Amtenbrink is involved in a German plot to drop cholera germs into England's water supplies.
Dirk manages to be sent to Ahlhorn (by the Germans) as a civilian security agent, where Zeppelins are being constructed. Dirk sabotages the Zeppelins with a fire, and is discovered to be a British agent.
When suspicions fall on them, they arrange to be picked up at sea at night - Kingston makes it but Hambledon appears lost at sea.
Kingston (as Dirk) returns to Germany, this time with agent Denton, who assumes the identity Ludwig Wolff.
Kingston matures through his adventures, and begins to regret marrying Diane; waiting at home for him.
This is the first Tommy Hambledon novel, however, the focus is not on him - but his protegé Michael Kingston. This is a not a slick sexy James Bond spy novel, it is more like a police procedural showing the not-always-exciting steps in intelligence work. It is somber at times, especially as it nears the end. They make mistakes and feel regret for them.
The first chapter is really the end of the story - chapters two forward are told in flashback.
Although I really enjoy the later Hambledons which are much lighter and funnier, it is good to see the genesis of the Hambledon story.
The sequel to this book is A Toast to Tomorrow, a.p.a. Pray Silence.