Villainous conspirator Sara Summers
Sara Summers (Kate Reinders) is a villainess from "Ancient History," episode 2.05 of Instinct (airdate July 28, 2019).
Sara Summers' brief backstory was revealed during her encounter with Dr. Dylan Reinhart and Lizzie Needham: she was married to a man who was conning her, but during the divorce, Sara's estranged husband was represented by Thomas O'Hare, leading to Sara losing her case. An angry Sara harassed O'Hare as payback, which led to a restraining order filed against her, and O'Hare was found deceased, Sara was a suspect, but she denied killing O'Hare.
As it turned out, Sara was actually one of O'Hare's killers, with the other direct killer being a man named Lon Vicars, who was known for being a domestic abuser and whose ex-wife was represented by O'Hare. In addition, both Sara and Lon were under the orders of O'Hare's paralegal, Becca Horner, who blamed him for her sister's death due to O'Hare representing her father in the custody hearing and wanted revenge. Per Becca's orders, Sara and Lon killed O'Hare via scaphism; torturing O'Hare for 12 days before sealing him in between a pair of boats, only exposing his head, hands, and feet.
Lou committed suicide via cyanide poisoning after confessing, but Sara's role was uncovered after Lizzie and Dylan went to the cabin where the torture happened, with Sara revealed as the owner. The villainess refused to talk, but after Becca's role as the mastermind was uncovered, Dylan and Lizzie portrayed Sara as a suspect writing a confession, with Becca witnessing Sara and confronting her after Sara entered Becca's interrogation room. Sara claimed that she was working on a word search with another suspect, and it was later confirmed as fact, as the "suspect" (revealed as Detective Clark) showed Becca the word search. In addition, Sara responded to Becca's scapegoating by outing Becca as the mastermind and showing Dylan and Lizzie recordings of their conversation, after which Sara was arrested (off-screen).