Former Marine Shooter and DIA agent Robert McCall (Denzel Washington) now leads a simple life in an apartment complex in Massachusetts, working as a driver at a company similar to Uber. In his spare time, he continues to help the helpless who find themselves in difficult situations, being assisted by a friend named Susan Plummer (Melissa Leo). One of McCall’s loyal clients is Sam Rubinstein (Orson Bean), a Holocaust survivor, looking for a painting of his sister who was separated when sent to different camps.
When he discovers that the apartment complex has been vandalized, McCall is in love with Miles Whittaker (Ashton Sanders), a young resident with a troubled past but with great artistic talent. One day, Susan is summoned to investigate an apparent suicide murder in Brussels with DIA agent Dave York (formerly McCall’s partner), Dave York (Pedro Pascal). During a race, McCall meets a killer who claims to be just a passenger he removes and gathers all his information and useful things.
The following morning, McCall visits York residence, looking for help to break an encrypted code to get information on the last contact in the person’s phone. McCall makes a disturbing discovery when he manages to decrypt the phone and begins his revenge mission to those involved in killing a good friend of his and trying to kill him. Despite threats from a group of criminals, McCall is not intimidated and is determined to eliminate everyone.