Ein gefährliches Spiel (1988)

Years after a desperate teenage Linda gives up her baby for adoption, she finds herself face-to-face with Martin, a young man claiming to be her long-lost son. Linda embraces Martin and in him finds a welcome reprieve from her unhappy marriage to the neglectful Henry. But soon Martin grows violent and becomes obsessed with Henry -- a philandering man whose only offspring is an expansive model train set that devours his waking hours.