Jimmy and Arthur have been friends since they were cubs in 1926. Life is good until their friend, Mr Zimmerman, is attacked at a football match and viciously beaten by three fascists. Two of the assailants are caught and sent to prison; the third escapes punishment until the boys discover his identity.
Forgiveness is not an option.
They only meant to knock him out, but half of his skull is never found.
As the boys discover amateurs don't get away with murder, the shadow of the hangman is too close for comfort.
It takes a world war, the special unit of MoD 1, an unarmed combat expert with a trilby hat and Mr Churchill's little problem with the French fleet to sort it all out.
N.B. This is classified information. Tell no one.