Darkness at the Edge of Town — Jennifer Harlow

A complicated, charismatic forensic psychologist tries to rescue her brother from the clutches of a maniacal cult leader in this edge-of-your-seat psychological thriller from the author of Beautiful Maids All in a Row.
 
After catching an infamous serial killer, Dr. Iris Ballard has become a TV sensation. Exhausted from her appearances on the talk-show circuit, she's looking forward to some quality time with Luke Hudson, her former FBI partner and on-again, off-again lover. The last thing Iris wants is to get pulled back to her dying Rust Belt hometown, but after the frantic call from her mother, she doesn't have a choice.
 
Iris is a disgrace in Grey Mills, Pennsylvania, but her twin brother has gone and outdone her. Billy has abandoned his fiancée, drained their checking account, and quit his job to join a cult called the New Morning Movement. Expecting to find something sinister at play, Iris is eager to destroy the quixotic hold they have on her brother. And that means outwitting the cult's cunning, sadistic founder, Mathias Morning.
 
Iris has logic and reason on her side. But Mathias doesn't play by society's rules. Just as Iris begins to lose hope, her investigation leads her to cross path with the DEA. And now she needs to save Billy's life before they're both caught in the crossfire.
 
Don't miss Jennifer Harlow's first electrifying Iris Ballard thriller:
BEAUTIFUL MAIDS ALL IN A ROW