Fletcher's Folly is an exciting romance-cum-mystery thriller. The heroine, Rebecca Valentine, takes a job as secretary to a female author and finds that the author lives on an island in the middle of the largest lake in New Hampshire. The young man who takes Rebecca to the island disappears from it and Rebecca cannot find him. Meanwhile, the author's brother flirts with Rebecca and she finds herself greatly attracted to him. But who is the mysterious figure locked away near the top of the castle tower? And who is the person apparently performing strange rituals in the middle of the night?...