The Captain Finds the Key is the exciting conclusion to a trilogy that began with The Captain Takes a Wife and continued with The Captain Seeks the Lost.
As the story opens, Captain Harry Richardson and his friends and family are still reeling from events that occurred when a stranger came to Choestoe to threaten Harry's wife and kidnap his son. In some way that he can't understand, Harry knows that all the frightening events of the past two years are related. The man who is behind it all is called "the Boss," and he is so feared by his followers that none of them will call him by name. The deacon who killed the sheriff may get away with murder if something isn't done to bring him to justice, but is he the Boss, or is there someone else out there who is calling the shots-someone even more frightening than the deacon? Harry is determined to find out. Then he receives a warning note:
Harry read it aloud. "If you care about your boy, don't try to find me." Ned looked at the note over Harry's shoulder. "That's [his] handwriting," he said. "No question about it. What are you going to do?" Harry's voice was quiet, but dangerous. "I'm going to find him." Ned nodded. "That's what I thought you'd say."