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Review

The Undertow Club Is a Locked-Room Mystery With Ice Water in Its Veins

Beatrice Lang's debut sets a classic puzzle inside a changing hut at a century-old winter swim club. The clues are fair, the cold is real, and the cast is a little too crowded.

By Julian HartSeptember 18, 2026 · 4 min read
A white lighthouse above a frosted coastal field
The Undertow Club takes place over one frozen January week in Gullhaven, Massachusetts. Photo illustration by RedSquibble.

On the second morning after Edith Marsh is found dead in the changing hut, the members of the Gullhaven Winter Bathing Society go back into the water. It is twenty-six degrees on the shingle. Nobody talks. They walk in together, as they always have, to their knees, then their waists, then under, and they come up gasping and furious and alive. "We did not swim for her," Beatrice Lang writes. "We swam because it was Tuesday, and because none of us could think what else to do with our bodies."

It is a startling scene to find in a mystery, and it signals that The Undertow Club, Lang's first novel, is after something more than a clever solution. It has one of those as well. Edith, who revived the club in 1979 when it was down to six swimmers and was called its founder ever after, is discovered inside the small wooden hut on the beach with the door bolted from within. The only window is frosted and painted shut. Forty-some members were standing on the stones outside. Every one of them had a reason to be there, and several had a reason to want Edith gone.

A town you can feel on your skin

Lang swims year-round herself, and her descriptions of cold water are the best thing in the book. She knows how fingers stop working after four minutes, how breath goes short and then long, how the body burns for an hour afterward like it has been scolded. Gullhaven, her fictional Massachusetts seaside town, is built with the same care. There is a diner that opens at six for the swimmers, a harbormaster who keeps the tide book in pencil, and a post office where everybody's business arrives before the mail.

The club itself is a lovely invention. Its members include a retired pipefitter, a fourth-grade teacher, a pair of feuding sisters in matching wool hats, and a young marine biologist who joined for the science and stayed for the gossip. Our guide through all of it is Clare Dunning, a former insurance adjuster in her sixth winter with the club, who narrates with a dry, exacting eye. "I spent twenty years deciding whether people were lying about water damage," she tells us early on. "It turns out that is most of what a detective does."

"Nobody ever locked the hut. That was the first thing that was wrong, and for three days it was the only thing any of us could see."

Fair play, played fairly

The puzzle is a true locked room, and Lang plays it straight. Every clue is on the page. A towel folded when it should not have been. A tide table with one date circled. A thermos that is somehow still warm. I guessed part of the solution around page 200 and was pleased with myself for about ten pages, until Lang showed me I had guessed the wrong part. The final explanation is ingenious, rooted in the physical facts of a small wooden building in extreme cold, and it does not cheat.

The characters, too, are better than the genre requires. Harold Pike, who tried the door first, is a gruff man with a secret that turns out to be sadder than anyone expected. Wendy Coyle, the teacher who screamed, is given a long and tender chapter about why she started swimming in the first place.

Too many robes on the shingle

My reservation is the size of the cast. Lang introduces nearly twenty named swimmers in the first eighty pages, many of them in a single chapter set at the club's annual meeting, and I found myself flipping back to remember who was the dentist and who was the dentist's ex-wife. A list of members at the front of the book would have helped. Better still, a few of them could have been cut. Several suspects exist only to be cleared, and the middle third loses momentum as Clare works her way down the roster.

The motive, when it arrives, is also slightly thinner than the method. The how is elaborate and satisfying. The why is a little familiar.

Out of the water

Still, the last chapters are superb, and the final image, of the club walking back into the sea on the first Sunday after the truth comes out, carries real weight. Lang understands that a community is also a kind of locked room, and that everyone in it has seen more than they say.

"The water does not care who you are," Clare says in the closing pages. "That is why we trust it."

The Verdict

The Undertow Club asks a little too much of its reader's memory in the early going, and its motive does not quite match its method. But the puzzle is honest, the cold is vivid, and Gullhaven is a town I would happily visit again. Lang has written a fine debut and, I suspect, the start of something longer.

The Undertow Club by Beatrice Lang (Bellwether, 320 pages, $27.99) is out now.

About the writerJulian Hart

Senior writer. Julian profiles debut novelists and the lives they write around. He spent a decade as a features reporter at newspapers across New England.

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