Matthias: The Ghost of Salvation Point by Jodi Auborn

Ten-year-old Dylan is excited when his father inherits an old lighthouse and cottage in Maine. Dylan and his family get to live there all summer! He goes sailing on the bay, explores the small town down the road, and searches for a legendary pirate treasure that was said to be buried nearby.

After mysterious things start happening at the cottage, Dylan meets Matthias, a…