The story begins with Mrs Smith, a working class housewife. She has three children; Mary, Jack and William. Mrs Smith becomes concerned about Jack who is having problems breathing and goes to see Dr King in his surgery. Dr King then visits Jack, diagnosing a bad case of diphtheria. He gives Jack an injection to his abdomen. He organises a swab and the laboratory technician is shown preparing the culture and placing the samples in an incubator. Jack goes into hospital; Mrs Smith is seen in the waiting room looking upset. The surgeons operate on Jack; placing a metal tube in his throat so that he can breathe. Jack is in the hospital bed; steam is directed across him to aid his breathing further (he has diphtheria of the larynx). The boy in the adjacent bed is paralysed and is fed through his nose. Overnight Jack's condition deteriorates. Meanwhile back in the laboratory the samples are viewed, discovering diphtheria germs (a still image is used). Jack dies, freeing the hospital bed for another child with diphtheria... the viewer is then asked whether they want their child to take his place?