Dark Corners by Megan Goldin

Rachel Krall, the true crime podcaster star of Megan Goldin’s acclaimed The Night Swim, returns to search for a popular influencer who disappears after visiting a suspected serial killer.

Terence Bailey is about to be released from prison for breaking and entering, though investigators have long suspected him in the murders of six women. As his release date approaches, Bailey gets a surprise visit from Maddison Logan, a hot, young influencer with a huge social media following. Hours later, Maddison disappears, and police suspect she’s been kidnapped—or worse. Is Maddison’s disappearance connected to her visit to Bailey? And why was she visiting him in the first place?
When they hit a wall in the investigation, the FBI reluctantly asks for Rachel Krall’s help in finding the missing influencer. Maddison seems to only exist on social media; she has no family, no friends, and other than in her posts, most people have never seen her. Who is she, really? Using a fake Instagram account, Rachel goes undercover to BuzzCon, a popular influencer conference, where she discovers a world of fierce rivalry that may have turned lethal.
When police find the body of a woman with a tattoo of a snake eating its tail—identical to a tattoo Rachel had seen on Bailey’s hand—the FBI must consider a chilling possibility: Bailey has an accomplice on the outside and a dangerous obsession with influencers, including Rachel Krall herself. Suddenly the target of a monster hiding in plain sight, Rachel is forced to confront the very real dangers that lurk in the dark corners of the internet.