UMAR revolves around three senior citizens -- Iqbal [Kader Khan], Chandrakant [Prem Chopra] and Rajpal [Satish Kaushik] -- who live in London with their families. Insensitively treated by their children, all three are humiliated and insulted all the while.

Enter Shashank [Jimmy Shergill], who has grown up to respect his elders. Treating the senior citizens with affection and respect, Shashank quickly wins a place in their hearts. Shashank falls in love with Sapna [Shenaz Treasurywala], who happens to be the daughter of a rich businessman [Shakti Kapoor]. But Sapna's dad does not approve of this relationship because of Shashank's status.

Shashank gets falsely framed for the murder of his lady-boss. The court finds him guilty and puts him behind bars. Shocked by the sudden change of developments, the three senior citizens plan his escape when he is being taken to prison. Shashank manages to escape, but is shot in the process.

Shashank is given shelter in Iqbal's house, but when Chandrakant and Rajpal's children find out about this, they complain to the cops, hoping to win a reward in the process. To avoid any unpleasantness between the senior citizens and their respective families, Shashank decides to leave. Instead, all three walk out with Shashank. How the senior citizens clear Shashank's name forms the remainder of the story.