Leon and Ursula are siblings, growing up in a wealthy mansion with their parents. Their father is a stern, analytical and curious medical doctor, who often means well but can be eccentric, creepy and even at times frightening, which influences the children as they grow up. Their mother, neurotic, abusive and obsessed with cleaning and hygiene, is constantly scrubbing floors and keeping the house spotless. As a result, Leon and Ursula have very few friends and spend most of their childhood isolated, coming to rely on each other for companionship. One day, Ursula's best friend, a sexually-experienced schoolgirl, gives Ursula a copy of a pornographic magazine, which Ursula sneaks into one of the bedrooms at home. Leon discovers her with it, and the two children giggle at the magazine and explore it, only to be caught by their mother. Despite the children not having actually done anything sexual, the mere existence of the offending magazine causes their father to take an interest in the children's proper sexual education. To explain sex and gender to the children, he uses ventriloquism to get his medical anatomy mannequin, named "Pin" (short for "Pinocchio") to "speak" to Leon and Ursula about "The Need" (a euphemism for sexual desire). Their father often uses Pin to entertain his other child patients during medical appointments so that they won't be frightened of doctors, a benign parlour trick, but while Ursula learns to recognize this as a trick, Leon does not. He fully believes that Pin is alive and speaking to him.
