Another Firefly reunion is in the works on an upcoming episode of ABC's Castle!

Nathan Fillion, who plays the titular Castle, is set to reunite with Jewel Staite in the upcoming 20th episode of the season on Castle. Fillion played Mal Reynolds on Fox's short lived but cult classic Firefly, while Staite played Kaylee Frye.

Staite is set to guest star as the director of a Shakespearean Broadway production in episode 8.20.

"Episode 20 is our nod to Shakespeare and our nod to Hollywood action stars going to do Broadway with mixed results," Castle co-showrunner Alexi Hawley said in a new interview with Entertainment Weekly. "Jewel Staite came to play with us as the director of this doomed Shakespeare play."

The episode is aptly titled "Much Ado About Murder," according to TVLine, and is set to air on May 2.

"There are some great scenes between her, Nathan and the boys," co-showrunner Terence Paul Winter told the publication. "She came to play, she was really great."

Fillion has reunited with other Firefly cast members in the past on Castle. Adam Baldwin (who played Jayne on Firefly) had a recurring role as Detective Ethan Slaughter. Summer Glau (who played River on Firefly) just guest starred as Kendall Frost in a March episode. Then there's Gina Torres (who played Zoe), who appeared in a season 5 episode of Castle.

Should we expect future guest appearances from Alan Tudyk, Sean Maher and Ron Glass (a.k.a. the rest of the Firefly cast) in the future? That remains to be seen.

In the mean time, Castle returns for another new episode this Monday. The episode centers on Hayley (Toks Olagundoye) and her involvement with the cyber world.

"After Hayley does a favor for an old friend, she finds herself implicated in a killing and cyber-terror attack," the plot synopsis for this episode reads. "Now, Beckett [Stana Katic] and Castle must rush to solve the case and clear Hayley's name

Castle airs Mondays at 10 p.m. ET/PT on ABC.

Check out the promo for the next episode of Castle here:

Tags: Castle television ABC