Keeping up with the title, Union Leader, the film revolves around the struggle that a man named Jay, who undertakes to give his workers the rights they deserve. Jay who works in a chemical plant is upset by the working conditions being provided to the workers. His anger is instigated when he sees these workers dying due to inhaling harmful chemicals. He also realizes that their current union leader is working along with their mill owner and refuses to take the side of the workers.
But Digant’s campaign leaves the owner and their current leader Manoj miffed and they kill the worker in order to save themselves from any further trouble. However, this prompts Jay to change his decision as he goes on to participate in the union leader elections and even wins. But his struggle with the management over the workers’ plight and their dire need for medical aid continues. He soon realizes that the entire upper management is corrupt and soon their factory shuts down.
On the other hand, according to information provided by his nurse friend Rita, Jay finds fake medical reports created by the factory managers of their workers in order to prove that the chemicals manufactured by them aren’t harmful. With the help of Rita, Jay gets to the original medical reports on the basis of which he drags the factory owners to court.
Will Jay succeed in his venture or will the wealthy factory owner yet again walk free despite heinous crimes they have committed is what forms the rest of the story.