In the Wrong Hands (1996)

After Sabine died in a car accident Thomas has to take care of their son Tobias. Sabine and Thomas had never been married, so Dorothea, Sabines mother, starts a custody suit against Thomas to get Tobias. But Thomas doesn't want to loose his 8-year-old Tobias. So he charges the lawyer Bekcmann. They find out that Dorothea is a psychopath. Tobias who is living at his grandma's, is in huge danger, but nobody wants to believe them.