Many years before, ten Harvard students hazed freshman Paul Chapin so severely that he was crippled for life. Chapin is now a famous novelist but remains embittered. After two of the former Harvard students are killed, the remaining eight receive threatening notes. Professor Hibbard, one of those involved, fears that he will be next and asks Nero Wolfe to help. Evelyn Hibbard, the professor's niece, is in love with Chapin's brother Mark, who warns Hibbard to stop persecuting his brother. The next day, Hibbard disappears, and Wolfe calls a meeting of the others. All agree to attend except Pitney Scott, a taxi driver. From banker Ferdinand Bowen, one of the classmates, Wolfe learns that the two victims were penniless at the time of their death. He tracks the threatening notes to a typewriter at the Harvard Club, which any of the men could have used. Wolfe orders his assistant, Archie Goodwin, and two other men to watch Chapin's apartment and they discover that someone else is also watching Chapin. Wolfe learns that Agnes Burton, the wife of Dr. Burton, another of the Harvard classmates, was once involved with Chapin. When Dr. Burton is killed with his own gun, Chapin, who was in the house at the time, seems like the logical suspect and he is arrested. Chapin refuses to defend himself, but Wolfe clears him when he demonstrates how the murderer must have hidden in a closet in Burton's home and timed the fatal shot to coincide with Chapin's arrival. Later Mark, who resents the persecution of his brother, lures Archie to his home, drugs him and kidnaps Wolfe at gunpoint. By the time the police catch up with him, Wolfe has calmed Mark. Calling another meeting of the classmates, Wolfe unmasks the mystery man who has been following Chapin. It is Hibbard, who went into hiding for protection. Wolfe identifies Bowen as the killer, and states that although Chapin sent the letters for revenge on his hazers, Bowen murdered the men after spending the funds they had entrusted to his care.