'Mesmerizing... I loved it' Graeme Macrae Burnet, author of His Bloody Project

'Impossible to stop reading' Mariana Enríquez, author of Our Share of Night

In this deliriously inventive twist on The Strange Case of Dr Jekyll and Mr Hyde, Argentine Diego Muzzio infuses classic gothic atmosphere with disturbingly modern psychological horror.

In an old sanatorium on the outskirts of Edinburgh, Dr Edward Pierce develops experimental therapies to treat patients traumatised by the First World War. Late one night, he receives a visitor who asks him to take on a bizarre case: David Bradley, an engineer who was sent to inspect the conditions of a lighthouse on a desolate island in southern Argentina. This once rational, disciplined man returned completely mute, his body overwhelmed by a single compulsion: to swim and swim, in any environment, to the point of total exhaustion.

As Pierce becomes fixated on Bradley's diary, a macabre record of his increasing derangement, he explores strange new treatments in which the lines between doctor and patient begin dangerously to blur.