Baker Dill has been slowly unraveling following the sudden appearance of his ex-wife Karen, who has tasked him with killing her abusive husband. Initially resistant to her pleas because of his obsession with catching an elusive giant tuna, Baker is worn down by the series of visions that he receives from Patrick, his son with Karen, with whom he seems to share a telepathic connection.
Reid Miller introduces himself as a representative of a fishing company that wants to give Baker a fish tracker free of charge. But he lets something slip as Baker tries to push him out of his house: "I am the rules," Reid says. He continues to babble, revealing that he knows all about Baker's obsession with the tuna called "Justice" and his intention to kill the man abusing his ex-wife. Is he an alien? A prophet? No, Reid is literally the "rules" of a video game.
Baker Dill is not a real person, but a character in a fishing video game that his son has been tampering with to play out his fantasies of killing a digital version of his abusive stepfather. Baker is based on his father, who had died in the Iraq War. But Baker retains all those memories of his son and his time in the war, and for some reason, can hear his son as Patrick inputs the code that changes a mundane fishing game into a murder scenario. Naturally, Baker undergoes a crisis of identity and free will, but decides to obey his son anyway and go through with killing the abusive husband, despite the game's various NPCs trying to thwart him — including at one point his first mate Duke hiring a group of gangsters to break the husband's hands so he can't fish.
Throughout the film, Patrick is shown in his room playing the game while stepfather beats his mother in the next room over. The twist reveals that these weren't flashbacks to different moments when Patrick fled to his game to escape his stepfather's violence, but one long scene that bookends the movie. And as video game Baker kills the digital stepfather, Patrick picks up a knife in reality to kill the one next door.
Written and directed by the creator of Peaky Blinders.