Plot
Five years after the first film, Stephanie Smothers is a famous true crime vlogger, an amateur detective and has written a book about her friendship with Emily Nelson and her subsequent imprisonment. At a book signing, Emily appears, as she is filing an appeal. Marrying her old friend Dante Versano, a wealthy Italian from a mafia-connected family, she asks Stephanie be her maid of honor. Emily pressures her to accept, promising increased book sales and threating a potential lawsuit.
Arriving in Capri with Dante and Stephanie's agent Vicky, they reunite with Emily's ex-husband Sean and son Nicky. Also there are Emily's mother Margaret and her aunt Linda, as well as Dante's mother Portia. The latter accuses her of marrying into the family for money. At the pre-wedding lunch, a bitter and intoxicated Sean has a heated confrontation with Dante.
Stephanie and Emily reconnect at her "bachelorette party", where she is the only guest. Upon returning to the hotel, Stephanie finds Sean murdered in his hotel room, which the local police write off as an "accident". Suspecting Emily's involvement, Stephanie follows her the next day, but an American tourist distracts her.
The 'tourist' introduces herself as Irene Walker, an FBI agent investigating Linda. She shows Stephanie a photo of Linda talking to a mysterious woman with Emily's tattoo. They are interrupted by Dante, who Stephanie later sees in a heated discussion with Matteo Bartolo, a member of the Versanos' rival family.
Emily and Dante are married. At the reception, he overtly burns their prenuptial agreement, declaring it as a gesture of peace between the Versanos and the Bartolos. Later that evening, Stephanie follows Dante as he leaves the reception, only to witness him being shot dead.
Portia accuses Emily of murdering him, while Linda casts suspicion on Matteo, who vehemently denies it. With Emily's presence accounted for, and Stephanie being the only witness to the murder she is branded the prime suspect. She is placed under house arrest while the death is investigated.
Stephanie meets with Emily, but soon realizes from her odd behavior that she is Charity, the third of the triplets that included Emily and her late sister Faith. Charity stabs herself, framing Stephanie for it. Stephanie is freed from her captivity by Isabella, a housekeeper paid by Irene. Entering Margaret's room; she reveals that Charity's stillbirth was faked by Linda, a con artist who raised her as her own.
Stephanie leaves the hotel and meets Irene, but before she can reach a safehouse, Irene is fatally stabbed by Charity in disguise once again framing Stephanie. Meanwhile, Linda discovers from Margaret that Stephanie spoke with her, so smothers her with a pillow. Stephanie is taken to meet with Portia.
Portia injects Stephanie with sodium thiopental, convinced she and Emily conspired to kill Dante. Unable to get satisfactory answers, Portia orders her killed, but Emily rescues her. Linda had attempted to blackmail her and Dante, threatening to reveal that their wedding was a marriage of convenience to hide Dante and Matteo's relationship.
Upon refusing, Charity confronted Emily. Obsessed with her, she killed both Sean and Dante. Charity drugged her and married Dante in her place, with Emily only escaping because Charity forgot to drug her.
Charity, posing as Emily, livestreams wih Stephanie's phone, sending a coded threat to Emily and Stephanie that she will kill Nicky if Stephanie does not turn herself in. Stephanie and Emily confront Charity and Linda, who is holding Nicky at gunpoint. Linda plans to kill Stephanie, pinning the murders on her, with Charity assuming Emily's life, money, and position within the Versano family. Stephanie points out that Emily will also have to die, which Charity rejects. In the ensuing commotion, Nicky flies a toy drone into Linda's face, allowing Charity to take her gun and shoot her, sending her over a cliff to her death.
Emily convinces Charity to take her place in prison and responsibility for all of the murders. Stephanie returns home, writing a second book about the Capri murders and honoring Emily's wish to give Nicky a normal life. Emily remains in hiding in Italy, where Portia confronts her. Revealing she knew Emily and Dante's marriage was a sham and she did not commit the murders, she welcomes Emily into the Versano family. Then, she requests "a simple favor", handing her an envelope.
