O'Keefe will play Kristina Coterra, a sexy and voluptuous reporter who takes a liking to Castle (Nathan Fillion). Of course, last we saw the novelist, he was finally locking lips with Beckett (Stana Katic). Will Kristina come between them?
O'Keefe, who most recently recurred on Two and a Half Men, will appear in the second episode of the season, which is titled "Cloudy with a Chance of Murder."
Castle returns for its fourth season on Monday, Sept. 24 at 10/9c on ABC.