Bud Jablonski is a blue-collar dad who provides for his family apparently working as a pool cleaner. His real job is hunting and killing vampires.

While at work Bud sees a man leaving the house where he's working. He silently breaks into the house where he encounters two vampires, an elderly woman and a younger man, who lives there. Following a lengthy fight, he kills the vampires and pulls out their fangs with pliers. Bud tries to sell the fangs at a pawn shop, but the prices that Troy, the owner, offers are not enough to help him with his money troubles. Bud's ex-wife Jocelyn is planning to move to Florida with their daughter, who attends a private school with high fees. In order to pay the tuition, cover his debts, and buy his daughter braces, Bud is forced to return to the vampire hunting union.

Bud enlists his old army friend, "Big" John Elliot, to help him rejoin the union. The union boss, Ralph Seeger, initially refuses, citing how Bud had been previously kicked out of the union due to his risky and aggressive hunting style. He eventually is given a final chance but must work under strict conditions: He must only work the day shift, which does not pay well, and must be supervised by a union rep named Seth. Seth is tasked to look for, and report, any violations committed by Bud. Meanwhile, a vampire named Audrey finds the vampires that Bud killed. While searching for the man who killed the older of the two vampires, Audrey finds, tortures, and interrogates Troy. Before she kills him, she reveals that humans used to worship vampires as gods and plans to restore the old order by building homes and using them to establish vampire colonies so she can build an army.

Bud and Seth go hunting, and although Bud violates several union protocols, Seth does not report them after learning of Bud's aim to support his family with his earnings. After they find and destroy an unusual nest of vampires, Audrey contacts Bud and threatens his family, revealing that the elderly vampire was her daughter. Bud rushes to his ex-wife to save her while being pursued by vampires but fails to get there in time. His family is taken hostage by Audrey, and Seth is turned into a vampire. Now set on rescuing his family, Bud and Seth recruit Bud's neighbor, an outcast vampire named Heather, to help them assault Audrey's stronghold.

At the stronghold, they are joined by Big John. During the fight, John gets bitten and chooses to sacrifice himself so that Bud can save his family. Bud is no match for Audrey's superior speed and physical strength, but through a clever trick, he gains the upper hand, kills her, and saves his family. When Seeger arrives with backup from the union and tries to use Bud's numerous violations to kick him out, Seth uses his extensive knowledge of loopholes in the union's rules to prevent him from doing so. As the Jablonski family drives away, Big John climbs out of a manhole in the street showing that he survived the explosion.