Avril is a nun in the Baptist Monastery, which, although closed at the end of the 19th century, still exists. He is headed by a sadistic elder sister, Marie Joseph. The rules set by the sister are very strict. Avril doesn't know what life outside the monastery looks like - only her parents left her at the monastery door. The nuns raised her. There comes a time when Avril must spend two weeks in complete solitude. But it is before this ritual that Sister Bernadette reveals a secret to her - she has a twin brother. Avril goes in search of it ...