An eerie tale about Euphrasie Mercier who is the housemaid-companion of Elodie Menetret. When Euphrasie decides to let her two deranged half sisters stay for a visit, they get on Elodie's nerves and are asked to leave. Euphrasie knows that if her sisters enter the real world they will be institutionalized, so she strangles Elodie. They continue to live in the mansion, dodging any suspicion until a nosey relative pays a visit. It's not long before he figures out what has happened, but until they're caught the suspense builds to a dramatic chill. The book is based on a true story that occurred in France, when Euphrasie Mercier murdered her companion, Elodie Menetret, in 1886 to get money for her two insane sisters.