Aadhalal Kadhal Seiveer story is about Karthi (Santhosh Ramesh) and Shwetha (Manisha Yadav) are immature Engineering students. They move in the same gang in the college and soon Karthi falls for Shwetha who initially does not respond as she treats him more like a friend. However Karthi emotionally traps the vulnerable Shwetha by threatening to commit suicide. And soon Shwetha is eating out of Karthi’s hand and they spend some intimate moments in a sea side resort resulting in her getting pregnant. All hell breaks loose when their respective families come to know the truth. The immature lovers have to face the consequences.