In Boulder, Colorado, a serial killer, infamously dubbed the Swipe Right Killer, has been targeting unsuspecting women via dating apps. According to the intriguing true-crime podcast, Mark My Murder, the killer has managed to leave no fingerprints behind, which hints at a deep fascination with forensics and a distinctive affinity for rosé. It’s on the eve of her 30th birthday that Eva Vaugh, played by Lucy Hale, gathers with her closest friends: Kelly (Virginia Gardner), Robin (Bethany Brown), and Anthony (Jayr Tinaco). Recently, Eva is reeling from heartbreak after her long-term boyfriend, Jake (RJ Fetherstonhaugh), a police officer, has unceremoniously dumped her.
As the night unfolds, Eva's older sister, Valerie (portrayed by Laura Yenga), bestows upon her a home security system, underscoring her protective nature. This reveal is further compounded when Valerie shares the hurtful news that Jake is now engaged to another police officer. In a moment of self-discovery, Eva decides to dive back into the dating scene, creating a new profile. She connects with several men, including Kyle (Jedidiah Goodacre), an old acquaintance from middle school, and Mitch, a charming bar owner she encounters in a local watering hole. During her interaction with Mitch, she learns about his unusual circumstance of having no fingerprints due to a previous kitchen accident. Spurred on by some sibling rivalry and a desire to reclaim her independence, Eva ends up taking Mitch home for an intimate encounter.
The following day, an employee from the security company, Norman (a character of pivotal importance), shows up to assess the security setup and shows interest in Eva. He mentions he is pursuing night classes in forensics and even asks her out, which she happily accepts. Soon after, Eva finds herself on a somewhat awkward date with Kyle, where he orders a bottle of rosé and proposes they continue their rendezvous at his place; however, she denies his advance and instead meets Mitch again for another intimate escapade.
With every new date, Eva's friends and Valerie start to notice eerie echoes between her three suitors and the Swipe Right Killer. A brutal new murder reveals a chilling detail: the killer wears size 10 shoes. This shocking development prompts Eva to take matters into her own hands, leading her on a quest to figure out the unsettling connection between her dating exploits and the string of murders. Mitch's anger flares when he learns Eva has been dating other men, leading her to a startling discovery: his shoe size is 10 as well. The confusion escalates when she joins Kyle for a picnic, only for him to violently lash out at a man, revealing yet again that his shoe size matches that of the killer’s.
As the tension heightens, Norman installs the home security system and takes Eva out on a date. However, he abruptly leaves after getting a distressing phone call. Eva and her friend Robin's curiosity gets the better of them as they tail Norman to discover him exiting a house with suspicious plastic bags. They find Norman's sister, Lila, who uses a wheelchair, who explains his sudden departure. A dinner invitation ensues, but soon Eva discovers Norman's shoe size is also a fit, and she finds a single woman’s shoe in his belongings. When a conversation about Lila reveals itself, the atmosphere shifts, causing Eva to leave abruptly.
Convinced that something sinister is afoot with Norman, she shares her concerns with Jake at the police station, who reveals that the killer has a disturbing habit of collecting victims’ shoes. Eva, ever the investigative spirit, sneaks into Norman's house to collect hair and skin samples, relegating them to Jake for further scrutiny. However, when Norman shows up concerned about her strange behavior, she asserts her boundaries and orders him to leave, brandishing the threat of involving the police.
Feeling isolated and unable to reach Valerie or her friends, Eva seeks refuge with Kyle, who has been her connection to her newly installed home security system. However, she soon receives a startling voicemail from Valerie—that Kyle is married and has deceived her about his profession. Tensions culminate when Kyle tries to force himself on Eva; during the chaos, Kelly appears unexpectedly and ends up fatally stabbing him. Eva uncovers a stash of phones in Kelly's vehicle, belonging to the Swipe Right Killer’s victims. Kelly confesses her dark past, detailing how she killed her cheating husband’s mistress and turned to murder potential intruders into her life. As the situation escalates and Kelly lunges at Eva with a knife, Eva fights back, using a stiletto heel from another victim to stab Kelly.
The police are summoned shortly after, thanks to Valerie's tracking app set on Kelly's phone, leading to the apprehension of the murderer. In the aftermath, Eva makes amends with Norman, and they rekindle their relationship. Fast forward, Eva has successfully penned a best-selling crime novel and is now co-hosting Mark My Murder. During a live episode, she receives a surprising phone call from Kelly, who is now incarcerated.
