CHHALAANG is the story of a disinterested sports coach finding meaning in life. Mahinder Hooda aka Montu (Rajkummar Rao) is a PTI (Physical Training Instructor) in Sir Chotu Ram School in Jhajjar, Haryana. In his teenage years, he had participated in cricket and athletic tournaments from the same school. But he quit sports after he didn't make it to the state team. Similarly, he also left law when he realized that he'll have to read lots of heavy books. This is when his father (Satish Kaushik) recommended his name to the school's principal Ushal Gehlot (Ila Arun). Hence, she hired him. Montu is not quite interested in doing his job as he believes that sports are not going to help the students. He also indulges in other activities in school, one of them being assaulting couples roaming in a park. During one such session, he ends up harassing a middle-aged couple (Rajeev Gupta and Suparna Marwah). The next day, Neelima aka Neelu (Nushrratt Bharuccha) joins the school as a computer teacher. Montu gets attracted to her and this is when Neelu reveals to him that the middle-aged couple were her parents! She also blasts him for being the moral police. Montu realizes his mistake. Slowly, both Montu and Neelu grow closer. Montu wants to take the relationship to the next level. But before that can happen, there comes a twist in the tale. Inder Mohan Singh (Mohammed Zeeshan Ayyub), a certified sports trainer, joins the school as PTI. Montu is demoted to being an assistant PTI though his salary still remains the same. Montu obviously protests but the principal doesn't pay heed. Inder arrives and starts giving hard training to the students. He also gets friendly with Neelu, further angering Montu. Singh realizes Montu is jealous and taunts him. An angry Montu assaults Singh. The principal tells Montu to apologize to Singh. He refuses at first and then requests her to hold a competition between two teams of the school. One team would be trained by Singh and the other by Montu. Further, Singh will have the advantage of selecting the best students. Montu asks the principal that if his team loses, he'd resign and he expects vice versa from Singh. Singh gives his nod. The principal, too, agrees and selects three sports for the tournament - basketball, 400 meters relay race and kabaddi. What happens next forms the rest of the film.