Theerthayathra tells about the story of a young child, the son of Madhu whose mother has died and about his longing for mother's love. Everyday, along with his pet Alsatian, he expectantly waits at the river side for a Ferry which will bring back his mother.One night Sharadha is found unconscious near the river side. The villager's bring her to Madhu's house. The son thinks it is his mother and is overjoyed. She too loves him as her own son. Madhu is concerned about the "guest" who has started living in his house and who has been accepted by his son as his lost mother. Sharadha tells her story to Madhu. She was raised by a dancing women as her own daughter. When Sharadha grows up she is pressurized to become the mistress of a Thamburan, She refuses, escapes from a boat and is swept ashore in Madhu's village.One day the friend of the Thamburan sees Sharadha and starts blackmailing Sharadha & Madhu. Madhu gets nervous and decides to throw Sharadha out of his house. She pleads with him not to, as she has fallen in love with Madhu and his son. But he doesn't relent as he fears the villager's reaction.In the climax when Madhu accompanies Sharadha on the ferry to take her away from his home & life, his son shouts from ashore to bring "mummy" back. Madhu relents and the Alsation dog shoos away the blackmailer, ensuring a happy ending. A simplistic story, the main role is that of Madhu' son and his pet Alsation. Only children may find Theerthayathra worth seeing.The music by A.T Ummar is below average.