Ray Richmond contributes to Deadline’s TV coverage.

As the ABC dramedy Castle moves toward the conclusion of its fourth season, the question of when lead characters Richard Castle and NYPD Detective Kate Beckett (played by Nathan Fillion and Stana Katic, respectively) finally will do the deed took center stage. It was the burning question addressed at tonight’s spirited PaleyFest salute to Castle at the Saban Theatre in Beverly Hills, where creator/exec producer Andrew W. Marlowe was asked to spill the beans on how long the chaste dance toward the bedroom would last. “Do I know when it will happen? Yes,” he replied. “When it does happen, it will open up a lot of different areas in the storytelling. It will be the next evolution in the characters’ relationship.” Marlowe acknowledged that a lot of people believe the characters’ getting together physically could prove a creative kiss of death for the show, using the model of another ABC dramedy – Moonlighting – which famously imploded after David Addison (Bruce Willis) and Maddie Hayes (Cybill Shepherd) did the deed. “I’m not someone who believes in The Curse of Moonlighting,” Marlowe stressed. “Moonlighting fell apart because (the producers) couldn’t meet their delivery dates (and not necessarily because of the storyline). But there will come a time when we can’t keep these characters apart.”

What should happen between the characters when the moment finally arrives? “Kissing,” offered Katic. Added Fillion: “We’re definitely both ready for this thing to happen already. And when it does, I think it should be really clumsy, with the two of them knocking stuff over.” Yet Marlowe wouldn’t go so far as to say that we’ll soon see Castle and Beckett playing house together. “We can’t afford that set,” he assured. Fillion, charming as ever during the session, also discussed his excitement at being reunited with his Firefly costar Adam Baldwin on a forthcoming Castle episode. Baldwin will guest star as Ethan Slaughter, a “rough-and-tumble” detective who “it’s safe to say will be rearranging parts of my face,” Fillion quipped. He, Katic and Marlowe were joined in the session by costars Molly Quinn, Seamus Dever, Jon Huertas, Penny Johnson Jerald, Tamala Jones and Susan Sullivan. It was also announced during the event that a new series of original ebooks novellas from mystery writer Richard Castle will be published mid-year by Hyperion, with the first (entitled The Brewing Storm) coming in May.