Alice a sweet young girl arrives in a rich family who welcomes au pairs for their children's and the house work. The first night she hears noises and discovers the master of the house fucking with one of the foreign girls and his wife on the stairs. Soon she realizes that sex has an essential place in the life of the castle.
Young workers double penetrate the hostess, the three girls must experiment the observation of the male body and test with their hands, mouth and whole body the capacity of male erection. Every evening, Alice wrote her secrets in her diary: a man takes her ass at night in her bed; the householder has sex again with another au pair while his wife is leading introductory sessions in threesome. But is it her imagination or the detailed report of lewd activities in the house?