During the Second World War, a hospital in England houses a wing where Dr. Brett has devoted his life to finding a cure for cancer.

The guards in front of the hospital see a parachute fall nearby and investigate, expecting it to be a Nazi paratrooper. They find no person and no parachute, and when they hear a noise it turns out to be just a dog. Baffled, they return to duty.

The dog approaches the entrance and transforms into a man. He walks in and requests to see Dr. Brett.

The doctor's assistant admits the man, who introduces himself as Peter Grainger, a famous cancer patient. He meets with Dr. Brett and tries to discover what his treatment is. Once Grainger has established to his satisfaction that the doctor is on the right track, he tells him that he must die and all those who know of the doctor's cure techniques. Appalled, the doctor protests that his research is vital to man's survival; Grainger says he is doing just the opposite by destroying the one hope mankind has of achieving a totally adaptive ability that stems from the cell and growth behavior of cancerous cells. Grainger has achieved such a state, which allows him to assume any form at will. Grainger transforms himself into a bomb and destroys the wing of the hospital. Grainger reforms himself and leaves.

Later, the disaster is reported as another building destroyed during a German bombing raid.