Blake Porter, newly promoted at Coble & Roy, enjoyed his success and engagement to Krista Marshall until his boss Wayne Vincent abruptly accused him of leaking a campaign and fired him. With his reputation ruined, Blake scrambled for work while he and Krista decided to rent a room to cover their mortgage. After a bizarre psychic, Quillizabeth, warned that Blake would stab Krista in their living room, a seemingly ideal tenant named Whitney Cross from Cosmo’s Diner moved in. Tensions grew as Blake’s toiletries and food were consumed, strange thumps disturbed his sleep, and a relentless rash plagued him, which he traced to fragranced detergent he believed Whitney had used in their shared washer.

Household friction escalated: rotting food and a fruit fly infestation appeared, Blake found his phone in Whitney’s bed and lipstick matching a stain on his shirt, and their goldfish Goldy died in bowl water Blake swore smelled of bleach. Krista, increasingly trusting Whitney and doubting Blake, moved out temporarily. Blake’s work troubles worsened when his temp manager Kenny called Wayne and branded him a thief. Soon after, Blake discovered a bloodlike stain beneath his living room rug and learned from Detective Garrison that their neighbor, Herb Zimmerly, had been murdered by blunt force trauma with an antique clock—just as Blake noticed his own flea-market clock was missing. When Whitney told police Blake disliked Zimmerly and needled him about rage and insomnia, Blake’s alarm deepened.

Convinced Whitney targeted him, Blake investigated her background but found nothing online and then, at a laundromat, discovered limonene had been mixed into his fragrance-free detergent. After finding a hidden paper bag with three severed fingers in his kitchen, he obtained “Whitney’s” high school transcript and drove to Telmont, New Jersey, to visit her mother, Jeannette. There, Jeannette described Whitney’s lifelong cruelty, Jordan Gallo’s death after scandal and torment, and years of destruction tied to Whitney. Studying a family photo, Blake realized the girl Jeannette identified as Whitney was his fiancée, Krista—revealing the tenant “Whitney” was actually Amanda Lenhart using a stolen identity, while Krista was the real Whitney Cross. Reeling, Blake saw a post that Stacie Parker was missing, connected the severed fingers to Stacie, found a forged suicide note in his pocket, and suspected he had been poisoned by Krista’s cookies, prompting him to vomit them up.

Chapters from Krista’s perspective confirmed the truth: she had killed Jordan in high school, engineered Blake’s firing by stealing and selling his client files, and manipulated everything about taking a tenant. With hacker Elijah’s help, she pushed Amanda out of her prior housing, staged terrible applicant interviews, and recruited Quillizabeth to deliver an ominous vision. Krista systematically sabotaged the home—emptying toiletries and cereal, hiding apples to rot, spiking Blake’s detergent with limonene, forging notes to sow hostility—and later admitted murdering Zimmerly with Blake’s fingerprinted clock and abducting and killing Stacie, delivering “souvenirs” and blood to Blake’s kitchen and floorboards. When Elijah became a liability after providing forged IDs and a vial of tetrodotoxin, she killed him as well.

As Blake tried and failed to repair things with Krista and keep his job, Krista escalated: she planted evidence to suggest infidelity, set Blake and Amanda against each other, and embedded herself as a victim with friends like Becky. She returned her ring through Malcolm and prepared a final frame—poisoning Blake with tetrodotoxin via cookies to cause delayed respiratory failure, planning to kill Amanda and stage Blake’s suicide with the planted note and remaining poison in his room. Arriving at the brownstone ahead of Amanda, Krista expected to find Blake incapacitated, but he was missing. She found a voicemail and text from him that, to her, suggested she could still maneuver the evening to her advantage.

Across the months, every alarming event in Blake’s home traced back to Krista: the rash, fruit flies, lipstick and phone placement, hair in food, bleach suspicion, and the neighbor feud; the murders of Zimmerly, Stacie, and Elijah; and the grand manipulation that made Amanda seem both culprit and bait. The Telmont revelation exposed Krista as the true Whitney Cross, confirming that Blake had been living with a killer who intended to fulfill Quillizabeth’s vision of blood in the living room by framing him for murder and ending his life.