The book tells the story of how the Doctor returns from the moon. The first half of the book covers the lives of Tommy Stubbins, the Doctor's assistant, the family of animals in England waiting for his return, and how the Doctor escaped from the moon. The second half of the book deals with the quest of the Doctor for peace and quiet, so he can write a book about the moon and his experiences there. But the constant demands of his patients make the project impossible to complete, so the Doctor attempts to have himself put in jail so he will be able to write his book.