Velayudham (A.V.M. Rajan), an orphan and a devotee of Lord Murugan, lives in the Murugan temple of Pooncholai town with the support of the priest Ponnambalam (Senthamarai). The temple trustee (Major Sundarrajan) comes for a special Pooja and notices the ruby stone missing in the deity's spear. He blames Velayudham and beats him and threatens to send him out of the town if it is not returned by him the next day. An upset Velayudham pleads with Lord Murugan for justice and since the stone could not be traced, Ponnambalam gives his relatives contact in Coimbatore and tells him to leave the town to avoid getting any punishment from the trustee. The next day, Ponnambalam finds the ruby inside the temple and rushes to stop him but it is too late as Velayadham has already left by train. On reaching Coimbatore, he loses his bag containing the address of Ponnambalam's relative. Lost in a new place, he finds solace in a discourse happening there by Kirupananda Variar and believes that Lord Murugan will certainly help him.
While buying Lord Murugan's portrait from Paramasivam's (Nagesh) shop, Velayudham gets the address chit which he had lost and realizes that the person he was supposed to meet is none other than Paramasivam. Velayudham gets a job from Bhama (Sachu), a fruit shop vendor close to Paramasivam, and sells fruits on the roadside. He does a very good business and saves up all the money. One day he gets help from Maragatham (Sowcar Janaki) in getting the money due from her friends, who try to cheat him.
One day, Velayudham helps an old man (V.S. Raghavan) with epilepsy struggling at the Murugan temple. Velayudham's help and sincerity in taking care of the old man's briefcase full of money impress him and he offers Rs. I0,000/- as a token of his appreciation. Using that money, Velayudham starts a fruit stall, which becomes successful. He later starts a jewelry shop and many other businesses. He soon becomes a rich businessman in the city and helps many people with his wealth.
Velayudham helps to retrieve Maragatham's stolen chain from his shop by a thief and she is very grateful. He chances upon the temple trustee on the road and invites him for lunch and the trustee comes with his daughter who to Velayudham's surprise is Maragadham. They both like each other and the trustee notices this and proposes a marriage between them. The marriage takes place and they commence a happy life.
One day, Velayudham asks Maragadham to accompany him to the Murugan temple at his hometown for the annual Pooja but she refuses. She tells him that she is an atheist and Velayudham is God to her and her home is her temple. She does not believe in Gods and temples.
Velayudham is shocked and carries on with his plan. One day, Kirupananda Variar comes home and Maragadham refuses to take his blessings as she does not believe in sadhus also. Variar leaves a letter advising him to let her be for now.
Days pass by and Maragadham becomes pregnant. She delivers a very sick baby boy with birth defects. Velayudham is shattered and keeps praying to God and blames her disbelief. Velayudham requests her to come with him to the temples with the child but she refuses. A year passes by and all doctors give up on the baby and finally tell her that only God can save the child. Now Maragadham realizes that she cannot save the child without going to the temple and agrees to join him.
They both start visiting Lord Murugan temples across many towns with the child. One day, while Maragadham is bathing, a snake comes near the child and in desperation, she calls out Lord Murugan's name and a peacock appears and takes away the snake. She realizes the presence of God there and starts believing and joins Velayudham in praying for the recovery of her child. They both meet Kirupananda Variar and seek his blessings in one of the temples. Finally, they visit Tiruchendur temple along with another devotee (K.B. Sundarambal) and pray to Lord Murugan there.
They both plead to Lord Murugan by ringing the temple bell continuously for many hours and faint. Their prayers work and Lord Murugan (Baby Sridevi) appears as a child and rings the bell. The bell falls down, breaking the floor, and water seeps out on the child. The child recovers and becomes normal making everyone happy. Velayudham, Maragadham, and others pray to Lord Murugan for his blessings.
[from the book Pride of Tamil Cinema: 1931 to 2013 by G Dhananjayan, Blue Ocean Publishers, 2014]