Dr John Watson is back home, fresh from his time in the trenches of Flanders Fields and now his task is to help rehabilitate soldiers suffering from the crippling effects of shell-shock. But in the woodlands of the lush countryside, the government is building the secret weapon to end the stalemate on the Western Front. But then disaster strikes. After a training exercise, eight men are mysteriously struck down, seven of them dead. There is just the one survivor, and he's not talking. Clearly something is horribly wrong, and the army calls in the only man who can solve the mystery: Dr John Watson.