Aagathan sees Dileep teaming up with director Kamal for the second time. Dileeep had earlier assisted Kamal on the highly forgettable Pachakkuthira.The film also marks the return of Charmy to Malayalam, after her rather unsuccessful stint in Vinayan's Kattuchembakam. Tamil actor Sathyaraj too forays into this Malayalam flick as retired soldier. 

Aagathan is alleged to be a serious story that is different from the usual youngsters' stuff that is associated with Dileep and also unlike the light hearted entertainers that Dileep is associated with.Gautham Menon (Dileep), a software engineer, has spent his childhood in Kashmir while his father worked in a bank there. He moves to Bangalore after his family is killed in a terrorist attack. While in Bangalore Gautham meets Shreya (Charmy), a management student. Though they hate each other initially, the duo soon finds fondness for each other.

In the course of action Gautham is introduced to Shreya’s dad (Sathyaraj), a General who had earlier served in Kashmir and the story take a turn from here. The rest of the plot forms the crux of Aagathan. .