John Wick starts with his wife dying after battling some disease. Shortly after the funeral, he receives a puppy that she arranged for him to get so that he wouldn’t be alone. A couple days later, he’s out in his classic car when this Russian thug takes note of it. The thug asks how much, and John says that it’s not for sale. That night, the thug and a couple of his guys break into John’s house, beat him up, steal his car, and kill his dog.
The thug takes the car to a chop shop and the owner asks where he got the car and punches the guy. The thug says the owner will pay because his dad is the Russian mob boss. When the boss calls the owner asking why he punched his son, the owner replies that they stole the car from John Wick. The boss replies, “Oh,” and hangs up. When his son gets home, he beats him up and tells him that John Wick is the guy you send to kill the Boogeyman. When he met his wife, he asked to leave the business, so the mob boss gave him an impossible task which John apparently handled with ease.
While this is going on, John digs up the guns and money he had buried in his basement. The boss sends a dozen guys to kill him, and John easily kills all of them. He then goes to New York to stay in this hitman hotel, and he starts killing a bunch of the Russian mob to get to the son. Eventually, things get so bad the boss makes a deal with John Wick and tells him where his son is hiding. So John kills the son, and then starts back home.
The boss had put a hit out on John, but one of his friends – instead of killing him – had been helping him. So the boss kills him because if he had just shot John his son would still be alive. Then, like an idiot, the boss calls John and tells him that. So John goes and kills the boss.
The movie ends with a bloodied John breaking into a kennel to fix himself up. He then steals a dog that was supposed to be euthanized.