Ethir Neechal (1968)

Maadhu (Nagesh) is a destitute orphan who performs odd jobs in a multi-family tenancy for a living. For the services he renders, he's allowed to sleep under the stairs of the tenancy. He also attends college with the help one of his professors. Among few people who understand his situation, and are ready to help are Major Sundrarajan and Nair (Muthuraman). He overhears one of the tenants speaking to her husband of getting him married to their daughter (Jayanthi) who is said to be psychologically challenged. He forcefully makes his mind to love their daughter even before they propose a marriage, so as to calm himself that the girl is none other than the girl he loved and not some unknown psychologically challenged girl. How she proves that she's indeed a normal person and also helps Maadhu to prove his worth forms the rest of the plot.