Nowadays, we’d call it post-traumatic stress and suggest counselling. But in the aftermath of World War One there’s no one to catch Dennis Beaumont when he falls, no one with whom he can share his increasingly dark thoughts.

Demobbed, he returns to London, and what he hopes will be the continuation of his old life, which includes the fiancée he proposed to in haste and who, while he’s been away, has become a far more independent and ambitious woman, with plans to start her own business. But the war was more than just an interruption: neither Britain nor Dennis Beaumont can go back to how they were before.

A conscientious objector, he had been assigned a job as an ambulance driver, and the pivotal moment in his war came when a soldier named Stephen Lovell died in the back of his vehicle. With little else grounding him, and his fiancée now distant and cold, he imagines an unspoken bond developing between him and Lovell’s grieving sweetheart.

Beaumont perceives a division opening up in the country between those who have first-hand experience of the war and those, like the latest intake of students at his old alma mater, who have no way of understanding. It’s not surprising that he’s become fixated on the novel Le Grand Meaulnes, as the world he knew lives on only in memory. He can’t see a future that can incorporate what he’s been through, and the only solution he can find is to leave his old life completely behind. Moreover, although conscientious objector Beaumont may have refrained from killing, it’s as though he’s brought death back with him. In the course of the story, there’s a heart attack, a suicide and a murder.

The Harlequin won the 2015 Novella Award, its 120 pages examining the psyche of a man scarred by war, one whose thought processes might not have seemed too incomprehensible to other survivors of that great conflict. Previous books by Nina Allan have won or been shortlisted for science fiction prizes, and she gives a tiny nod to her more fantastical work in the shape of Vladek, an enigmatic figure who appears on the field of battle just when Beaumont needs him. It’s an angle that isn’t followed up, but hints that there might be more to what’s going on than PTSD. Consequently, a story which is already haunting and memorable nudges readers just a little bit further out of their comfort zone.