In the Castle episode “Backstabber,” Hayley Shipton (Toks Olagundoye) tags along with Castle (Nathan Fillion) when he’s called to a crime scene. When they arrive at the scene of the crime — the office of Manchester Energy — Hayley recognizes the victim. He was stabbed in the back and died instantly. In a flashback, we see Hayley giving the victim a box of breath mints which at the crime scene is peeking out of his pocket. Hayley pretends to be careless with the evidence, adding her fingerprints on the box. Hayley’s keeping a secret and it somehow involves a woman named Karla.
Karla Nielsen is portrayed by Bree Williamson. The Canadian-born actress is known for her roles on Blindspot (Abby), Chicago Fire (Beth), True Detective (Jennifer), Deception (Vivian Lawson), Haven with Nathan Fillion! (Claire Callahan), One Life to Live (Jessica Buchanan Brennan), and Gossip Girl (Brandeis). Castle airs Mondays at 10pm on NBC.