The hazardous sea ebbs and flows throughout this gripping debut psychological thriller. One day, 29-year-old Zena is discovered drowned close to the holiday home she has been sharing with her lover, Tom – but was her death an accident or murder? After hearing rumours that make her “unsettled, disturbed inside”, Tom’s new wife, Carmen, decides to discover the truth. Emphasising the gap between appearance and reality, surface and depths, Heathcote skilfully ramps up the dramatic tension: Tom is a man “trained to conceal his true feelings, to put on a veneer”, but his violent temper must sometimes storm to the surface. Despite some strained plot twists, this is an immersing story, reminiscent of Daphne du Maurier’s Rebecca, and the dead Zena exerts a powerful force. The “hidden currents” that keep us submerged in Undertow are not only those of the sea, but the fear and suspicion that swell catastrophically through the most intimate relationships.

Undertow is published by Quercus (£12.99). Click here to order it for £10.65