Fifty years ago a group of teenagers spent a weekend on Holy Island, forging a bond that has lasted a lifetime. They still return every five years to celebrate their friendship and remember the friend they lost to the rising waters of the causeway at the first reunion. Now when one of them is found hanged, Detective Inspector Vera Stanhope is called in. With the tide rising, secrets long hidden are finding their way to the surface, and Vera and the team may find themselves in more danger than they could have believed possible.