Indru Poi Naalai Vaa is a 1981 Tamil film written and directed by K. Bhagyaraj. A coming-of-age story of three carefree teenagers, complete with bell bottoms and thick-framed goggles of the 1980s, the film attained cult status among film buffs.
Pazhanisamy, Venkat and Rajendran are three friends who ogle girls. An innocent girl Jaya and her family shifts to the house opposite Pazhanisamy’s. The trio ogle Jaya from Pazhanisamy’s house window. When Venkat and Rajendran go out, Pazhanisamy selfishly locks the house and spends all day smoking and watching Jaya’s house. Venkat and Rajendran catch Pazhanisamy’s selfish act and 3 of them challenge to win Jaya’s love. The next day, Pazhanisamy notices Puppy, a toddler in Jaya’s house, near the road. He carries her and lies to her mother and Jaya he saved her from an oncoming lorry. The mother and Jaya thank Pazhanisamy for his kindness and Pazhanisamy voluntarily takes care of Puppy. He starts to help out Puppy’s mother in household chores to impress Jaya.
Rajendran is a college student and so, he purposely makes inappropriate sketches on the blackboard and pretends to scold his classmates for their immaturity. The Hindi teacher chances on this and is impressed. Rajendran takes advantage of the positive impression of him in the Hindi teacher’s mind and requests to join his tuition to learn Hindi. The Hindi teacher is none other than Jaya’s father. But the Hindi teacher tells Rajendran he will conduct his tuition in Rajendran’s house instead of his. Rajendran is dismayed by this. At his house, Rajendran annoys the teacher by not cooperating and seeking the support of his nagging grandmother. The teacher gets irritated to the point where he decides to teach Rajendran at his house. But the teacher repeatedly hits Rajendran when he makes mistakes and Rajendran plans to take revenge on him if Jaya fails to fall for him. Venkat gathers information about Jaya’s grandfather from the local shopkeeper and plans to trap him in a pothole during his early morning jog. His plan is to trap the grandfather and save him to impress Jaya. But the grandfather jumps out of the pothole himself, foiling Venkat’s plan. Venkat sends goons to beat the grandfather so he can put up an act of saving him but the goons get suppressed by him too. The grandfather is a martial artist and so, Venkat decides to learn boxing from him at his house. Jaya’s grandfather takes him in but the boxing training is strenuous for Venkat. If Jaya does not fall for him, Venkat plans to take revenge on the grandfather for his physical torture. The next morning, at 5 o’clock, Pazhanisamy sends a soothsayer to Jaya’s house. The soothsayer tells Jaya: at 7 o’clock, your future groom will cross your house in a black shirt and white pants. At 7 o’clock, Jaya waits outside her house for the groom. Pazhanisamy comes out in black shirt and white pants but is startled when Jaya cheekily lies to him the soothsayer told her the groom will be in white shirt and black pants. Pazhanisamy believes her and beats up the soothsayer, who swears he did not lie.
One day, Venkat submits a love letter to Jaya who is feeling mixed about it. Jaya’s sister arrives from her hometown and plans to stay there for several days. She notices the 3 friends carefully and surmises they are trying to win Jaya’s love. She tells this to Jaya. Jaya is in a dilemma on who she should choose as her love. The sister gives her an idea to resolve the dilemma. The next day, Jaya calls the 3 friends to meet at a park and tells all of them she was impregnated by a stranger several months earlier. By right, she must marry the stranger as he is the father of her child. The 3 friends are dejected. As planned, Rajendran and Venkat take revenge on the Hindi teacher and the grandfather respectively. But Pazhanisamy is still loyal to Puppy’s mother and impresses Jaya. Jaya decides Pazhanisamy will be her true lover.
Jaya’s father proudly tells her about his former student working in the U.S. and she sees his photo in the newspaper. Jaya then approaches Pazhanisamy and requests him to reunite her with the stranger who impregnated her. She gives the photo in the newspaper to Pazhanisamy and says he is the stranger. Pazhanisamy takes the photo and looks all around for the stranger. He stumbles on a gangster, who resembles the guy in the photo. Pazhanisamy persuades him to marry Jaya. The gangster plans to use the chance to sell Jaya as a prostitute to Arabia and agrees. Pazhanisamy brings Jaya to the gangster the next morning and Jaya is appalled to see her playful lie transformed into a threat. She admits the truth to Pazhanisamy and gives him a love letter she wrote. Pazhanisamy is relieved and apologises to the gangster. The dimwitted gangster and his equally dimwitted men kidnap Jaya and hurry to Arabia by jeep, thinking it is in Tamil Nadu). Venkat and Rajendran arrive, and together with Pazhanisamy, pursue the jeep to save Jaya. The trio fight the gangsters and soon, Jaya’s father and grandfather join the fight. Pazhanisamy saves Jaya and her sister lets them marry there itself. The newlyweds use the gangster’s jeep as their wedding chariot.