Charles Watkins, a professor of Classics at Cambridge University, has suffered a breakdown. Confined to a mental hospital as his friends and doctors attempt to bring him back to reality, Watkins has embarked on a tremendous psychological adventure that takes him from a spinning raft in the Atlantic to a ruined stone city on a tropical island to an outer-space journey through singing planets. As he travels in his mind through memory and the farther reaches of imagination, his doctors try to subdue him with ever more powerful drugs in a competition for his soul.