'I love an Erin Kelly book! The worlds she creates are so rich and alive' JANE FALLON

St Cordula's Convent, 1487. Sister Matilda is pregnant and has been banished from the convent: the only home she has ever known. Outside, the snow is swirling. She knows she will not survive a night on the Yorkshire moors. In despair, she climbs to the top of the Abbey and writes the words GOD FORGIVE ME in chalk on the wall, then throws herself down the stairs.

In 2024, life within St Cordula's Boarding School is changing. The last of the nuns is dead, the oldest convent school in England is about to merge with a local boys' school and a new deputy head, Fiona Fox, has arrived. The only constant seems to be the building itself, the iconic school uniform - nun-like navy blue hooded capes - and the words GOD FORGIVE ME, re-painted every year first by nuns and then by schoolgirls who believe that the spirit of Sister Matilda will keep the school safe as long as her words are never allowed to fade from the wall.

Only once in the school's history have the words disappeared, and when they did, the girls were gripped by a mass hysteria that saw them thrown to the floor by violent attacks of vertigo. At first, the epidemic was believed to be the work of spirits or devils: by the time a psychologist was brought in to explain the science, it was too late: a girl was dead. Only three people know the full truth and the scandal that was hushed up.

Fiona's new role seems to be starting smoothly, until another outbreak of vertigo drags the past into the light. Old superstitions rear their ugly heads, and the girls take it upon themselves to investigate the previous outbreak, putting the school - and themselves - in terrible danger...

'When it comes to deeply involving, twisty thrillers, Erin Kelly is in a league of her own' CHARLOTTE PHILBY

'Erin Kelly is quite simply one of the best crime writers around' JANE CASEY