Mystery of the Haunted Pool — Phyllis A. Whitney

It's a case of haunts along the Hudson in this spine-tingler by a master maker of tingles for the younger set. Leaving her family in New York at the start of the summer vacation, Susan Price comes up the river to the little town of Highland Crossing, where her aunt runs an antique shop.

A string of wooden beads…
A captain's log…
A strange face that appears -- then disappears -- at the bottom of a pool.

What is the secret of the old sea captain's mansion?
Susan Price and her brother Adam unravel the clues to a century-old mystery…and discover a fortune!