Footpath begins with Arjun narrating his story in flashback mode. As a child, he lived in a Mumbai slum with his father who was a workers' union leader. Two street kids Raghu and Shekhar, and their sister Sanjana were his best friends.
But one day his father was murdered by anti-unionists and Arjun took revenge helped by his friends. He fled to Delhi soon after. Cut to the present: 20 years passed, and police came to Arjun with a proposition. Raghu and Shekhar were drug dealers and police wanted to reach the top man of the crime ladder through them. Or else Arjun will be charged of past murder.
Reluctantly Arjun accepts the offer and joins Raghu's Mumbai gang. Side by side he hooks up with Sanjana who has estranged herself from her brothers. But the police inspector (Aman Verma) who gave the offer to Arjun in the first place has received an order to conduct an "encounter" of the two brothers. So Arjun must reach the "big fish" within 30 days if he wants to save his friends.