Aa Raathri(1983)

Ravi and Indu are a happily married couple who live in Trivandrum. On a train journey back from Ernakulam they meet a girl Radha. She ran away from home to escape from her abusive stepfather and her only hope is to find her cousin Venu in Trivandrum, but is unaware of his wherabouts. Ravi and Indu take her in to their house and decides to help her find Venu.