Prem (Ranbir Kapoor) is a happy-go-lucky person who resides with his parents in his small town and runs "Happy Club" - a club which aims at making people happy. Prem meets Jenny (Katrina Kaif) through a misunderstanding and the two become friends. Jenny is a sweet and simple girl, who was adopted and brought up by indifferent and uncaring parents who wanted to get her married off for their selfish reasons. Jenny is in love with her college friend Rahul (Upen Patel) while Prem has also fallen for her. Prem saves her out of her forced marriage but is he to confess his feelings to Jenny regardless of the fact that Jenny loves Rahul? How will this become ‘Ajab Prem Ki Ghajab Kahani’?