The story revolves around a bunch of college students living in a boy's hostel. The story unfolds over a period of four days in the hostel. Problems begin when a young woman enters the hostel.

The story of Action Hero Biju revolves around certain interesting episodes in the life of a young police officer, his personal and professional life. Nivin Pauly plays the titular role, Sub Inspector Biju Paulose, an officer in a Janamaithri Police Station. The situations take the story forward. Action Hero Biju is a realistic portrayal of a cops life, in contrast to the macho appearance seen usually in action movies.