The next day Mr. Dalrymple returned, having decided to let the Hardy boys take the case. He explains that he recently purchased the Purdy house and had been using a secret safe room there to find solitude; however he had received death threats delivered to the secret room while it was securely locked. The Hardy boys explore the Purdy house that night and see a man who looks like Mr. Dalrymple enter the house before they hear screams coming from the house and meet Hurd Applegate, whom the boys met while solving "The Tower Treasure" mystery, running from the house.