Death on a Rainy Sunday (1986)

Original title: Mort un dimanche de pluie

Thriller about a psycho looking for revenge. Bronsky is a paraplegic because of an accident at a construction site that was partly due to the head architect, David Briand. Many years after the accident, Bronsky shows up at Briand's residence with his family and his trailer looking for assistance. He and his wife insinuate themselves into the household without revealing their true identity. They start to work for Briand and his wife Elaine as a gardener and a babysitter with the sole objective of wreaking havoc on their lives and avenging Bronsky's disabilities.