The Chamber

Hats off to Will Dean. He's only gone and done it again. He's taken the locked room mystery and turned it on its head. For locked room read hyperbaric chamber.
Picture, if you will, 6 people in a very small chamber, locked in and breathing a mixture of helium and oxygen. Then one by one, they begin to die. Sounds like “And Then There Were None” crossed with Voyage To The Bottom Of The Sea.
This is no cosy mystery though. It's on-the-edge-of-your-seat, panic inducing, suspense. It is claustrophobia writ large. And oh boy, that ending. See, that's the thing I love about Will Dean. He never gives you a straightforward ending, but he does take you on quite the journey.