Simply put, someone is about to die on Castle.

Star Nathan Fillion told TV Guide this week that an extended family member of his character will meet his/her end on the show's September 27 episode.

"As in real life, death is sad, but it makes us all appreciate what we have around us a little bit more," Fillion said, while creator Andrew Marlowe added: "This will bring the family closer together."

Might the culprit be the serial killer Marlowe previously reported would be coming to the series?

That much is unclear, but we can confirm the victim will be one of the following:

• Chet, the boyfriend of Castle's mother, Martha;
•  Meredith, Castle's first ex-wife and Alexis' mother;
• Gina, Castle's second ex-wife.

Sound off with your best guess now!

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.