My name is Emma Brennan, and I never thought I’d find myself in this position — standing on a Cape Cod beach at sunrise, wondering which of my friends is a killer.

I came to the idyllic seaside town of Provincetown, to raise my young niece and figure out what to do next with my life. Eleven months ago my sister vanished off the coast of Ocracoke Island. No body, no answers. Just a teenage daughter left behind — and me. At the same time, the man I thought I was going to marry cheated on me with a cute young florist.

I joined the Tragic Wives’ Group — a tight-knit, cold-water swimming group with enough personal drama to fill a bestseller. And one of us has put it in a manuscript, spilling all our secrets. Then she disappears . . . leaving just a pile of clothes on the sand. She’s the second person I’ve lost in twelve months.