The year is 1884. London is being terrorised by a series of bomb blasts - even within Great Scotland Yard! Reluctantly, Sergeant Cribb attends a course in the science of infernal machines in a bid to gain expert knowledge of explosives and beat the criminals at their own game.

With Constable Thackeray the prime suspect, Cribb feels bound for professional and personal reasons to track down the truth at any cost. And very soon he is abducted at gunpoint by an Irish-American hammer-thrower and finds himself an unwilling but vital member of the Dynamite Party . . .