On Father's Day weekend, architect Evan Webber remains home to complete his work project and attend his physical therapy appointment for his injured shoulder while his wife and children go on a pre-planned vacation. His wife Karen, a successful artist, leaves her assistant Louis in charge of her sculpture that needs to be moved to an art gallery for her show.
Two young women, Genesis and Bel, knock on Evan's door during a rainstorm. Soaking wet, they tell him they are looking for the address of a party but their phones are not working. Evan allows them in to dry off and use the Internet. The girls play with the family dog, Monkey, and flirt with Evan while he orders an Uber for them. They disappear to the bathroom when their driver arrives. Evan brings them their clothes and finds them naked. He tries to convince them to leave, but they seduce him and he has a threesome with them.
The next morning, Evan finds that his wife's sculpture has been vandalised by the girls. He threatens to call the police, but they claim they are underage. Vivian, his physical therapist, arrives, but upon meeting Genesis who pretends to be Evan's lover, she angrily leaves. When Evan calls the police and begins to report a break-in, the girls agree to be taken home.
At night, after finishing cleaning the house, Evan is attacked and knocked out by Genesis. He wakes up tied to his bed as Bel climbs onto him and rapes him, while Genesis records them with Evan's phone. Evan breaks free and charges at Genesis, but she stabs him with a fork. She and Bel tie Evan to a chair with an electrical cord, torturing him into answering their provoking questions about his infidelity.
Louis arrives for the sculpture and discovers the girls' antics. He tries to free Evan, but has an asthma attack and realises the girls have taken his inhaler. He slips, hits his head on the sculpture, and dies. The girls turn Louis's corpse into a red sculpture and use both Evan's and Louis's phones to send text messages in order to give the appearance that Louis discovered that Evan had an affair with Louis's wife, gotten into a fight with him, which resulted in Louis's murder. They announce they are planning to kill Evan at dawn as punishment for his infidelity. They also reveal they have been spying on Evan's family long before the weekend, preparing every detail of their plot.
The girls dig a grave for Evan in the yard and trash the house. When they find his home defence gun, Genesis takes it and gives Evan a chance to escape if he can hide from them inside the house. Injured and exhausted, Evan fails after realising no one in the neighbourhood is at home to seek help from.
At dawn, the girls tie Evan up with a hose, bury him in the hole, leaving only his head above ground, and tell him they will crush his skull with a large stone. It misses his head as the girls reveal the entire ordeal was merely a "game": they never intended to kill Evan, nor are underage; everything they did was part of a hobby of seducing, victimising, and ruining the homes of married men with children who cheat on their spouses. Genesis uploads the video she recorded of Bel raping Evan to his Facebook profile, making him look like a paedophile. They depart for another victim and take Monkey with them, leaving Evan to his fate. Karen and the kids arrive to find the house ruined.