Naina (Deepika Padukone) is a shy and nerdy medical student. She studies constantly and always tops her classes, but she feels like an outcast. An encounter with an old classmate, Aditi (Kalki Koechlin), makes her realize that she wants more from life than high marks. Thus,she makes an impulsive decision to follow Aditi on a commercial hiking trip into the Himalayas, up to Manali. During the hike, she renews her friendship with other former classmates, Kabir Thapar aka “Bunny” (Ranbir Kapoor) and Avi (Aditya Roy Kapur). Bunny is a handsome charmer whose dream is to wander and discover the world. He does not plan to marry or settle down. During their trip, seeing Aditi’s silent reactions to Avi’s constant flirting with other girls, Bunny and Naina realize that she has a secret crush on Avi, but do not bring the matter to surface.