Ammai Kosam is a social darma based movie in which, There are four unemployed graduates namely Venkat (Vineeth), Ravi (Ravi Teja), Balu (Ali) and Venu (Siva Reddy).
For the past five years, they are been wasting their time by doing eve-tease and other unconstructive things. Soon they become an embarrassment for their parents.
Anjali (Meena) is a Gemini photographer and this foursome teases her heavily. Their crude behavior does not offend her and she teases them again. After some time they call for a truce and this foursome settle as thick friends with Anjali.
She spots a talent each in them and asks them to channelize their energies in that direction. Venkat is a good poet. Balu is a good cook. Ravi is a champ at bike riding. Venu is good at mimicry.
As these guys never moved close to any other girl in their past, they mistook her friendly affection as love. Each guy feels that she loves him.
On Anjali's birthday, this foursome pools some gifts by stealing stuff from their respective houses. When Anjali comes to know about that she acts tough and tells them to make a living for themselves instead of burdening their poor parents. Each guy proposes to her in isolation and she accepts all the proposals and promises that she would marry them if they start living on their own.
The rest of the story is about how these guys become responsible youth.