Frances Fisher is set to guest star as a potentially murderous fashion designer on the next episode of Castle.

Fisher will guest star as Matilda King, the editor of Modern Fashion magazine whose assistant is found murdered. This leads Castle (Nathan Fillion) and Beckett (Stana Katic) to enter the world of high fashion to try to determine the potential killer.

Fisher recently spoke with HollywoodLife.com about the role, saying that it was a "lovely" character to play. The actress said that most of her scenes were with Castle and Beckett.

"My scenes were mostly with the two of them," Fisher said. "What was really nice was to discover that Nathan is actually a lot like Castle! He's got a great sense of humor. And Stana is just lovely; we had some great conversations while we waited between takes. It was great just hanging out on set."

The big question becomes whether or not her character Matilda actually killed her assistant.

"She's certainly a suspect," Fisher revealed. "She runs her company with an iron fist."

Fisher explained that she did a lot of research for the guest part.

"I like to play different characters," she said. "I don't like the play the same thing twice, and this definitely was a first for me. ... I did as much research as I could, and then I used my own imagination to fill in the blanks. But if the script is well-written, which it was, then you have all the clues embedded."

The episode, titled Dressed to Kill, also features Beckett using her history in the modeling world to gain special access to "a very special wedding surprise," according to the official synopsis for the episode.

Castle airs Mondays at 10 p.m. on ABC.

Watch a promo for the next episode of Castle here:

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