Horis taftotita (1963)

John Ntonaventis has financial problems. One night, a strange type proposes him to impersonate the lost son of a rich family. In the family, who are convinced that he's their son, there is also a daughter, the presumed sister, who falls for him and causes the jealousy of her cousin. But behind the strange guy that proposed the whole scam there is a big secret hiding.