Riptide

Riptide is a novel by the American writers Douglas Preston and Lincoln Child, published in 1998. It is the only one of their books that stands entirely alone, with no characters shared with the rest of their work.

The novel is fiction, but it takes part of its premise from the legend of the Oak Island Money Pit, and it moves that site to a made-up place called Ragged Island about six miles off the coast of Maine. The pit there, known as the Water Pit, is said to hold the treasure of the pirate Red Ned Ockham, estimated to be worth close to two billion dollars, and to include a weapon called St. Michael's Sword, which reputedly kills anyone who looks at it.

The story opens in 1971, when Malin Hatch and his older brother Johnny, whose family owns the island, ignore the rule that keeps them away from the pit and go to look at it. Years later Malin comes back to Ragged Island with instruments and a crew to make a proper attempt on it, and the island proves as dangerous to them as it was to the men who dug before.