Doctor Watson returns home from the front. Memories of the battles in Flanders still haunt him, and now he is engaged in the rehabilitation of soldiers suffering from shell shock. But far from the trenches and battles, in the middle of a rural idyll, something terrible and mysterious is already waiting for him. There, engineers are developing a prototype of the weapon of the future, designed to turn the tide of the war in favor of Great Britain. But during one of the tests, disaster occurs. Under strange circumstances, seven soldiers die, and the only person who survived the incident is somehow speechless. And then Winston Churchill, Chairman of the Commission responsible for the secret project, instructs John Watson to find out the cause of the tragedy. The Doctor does not want to participate in political intrigue, but under pressure from the authorities he agrees when he learns that this case is connected with the fate of his best friend, Sherlock Holmes. Watson understands that he cannot trust anyone, but it soon turns out that he cannot even rely on his own reason, because all those who died went crazy shortly before their deaths.