The proof that ghosts exist / Matas, Carol

Molly and Adam, trying to help their dad avoid a family curse in which males die the day before they turn thirty-five, investigate a suspicious accident in which their father twisted his ankle, an apparition which keeps appearing at their dead grandfather's desk, and a mysterious nurse who is a little too interested in their family.

In this first book of the trilogy, siblings Molly and Adam learn that men in their family die the day before their thirty-fifth birthday. Their family decides to take a vacation at their cottage by the lake to make sure their Dad is safe and nothing goes wrong. Instead, everything goes wrong when their grandfather's ghost greets them at the cottage.