All is not well in St Dymphna's Abbey. A mysterious malady has swept through the halls of the once respected abbey, striking down all of the nuns in its wake.
The inquisitive Sister Felice was the first to succumb, but she is by no means the last. Sister Hilda, Sister Rosalind, and Sister Freya soon fall victim to this mysterious malady - and, in the end, even the venerable Mother Superior begins to sicken.
Sisters Jeanne and Josephine are the only nuns in the abbey who remain immune to the effects of this peculiar illness, but their attempts to aid their fellow sisters are in vain. With their fellow nuns dropping dead around them, one after the other, Jeanne finds herself despairing - and her despair turns to desperation when her beloved Sister Séraphine begins to sicken.
The ever-practical Sister Josephine decides to leave St Dymphna's to find a physician in the nearby village, but Jeanne's hopes are beginning to dwindle. With so many of her sisters dead, who's to say that any human physician will be able to save her precious Séraphine?
Time is starting to run out - and as it does, Jeanne begins to wonder. How far is she willing to go to save the woman that she loves?