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.

A skit on Jesus Christ brings out a change in good-hearted rowdy Cleetus along with revealing few surprises of his nature and his relationship with a neighborhood tailor.