One of the main characters on ABC's Castle is about to be a person of interest in a crime.

Would 'Castle' Really Continue Without Its Main Characters?

It is not known which series regular will be involved, but a new TVLine report reveals that it is a murder case. This will be revealed at some point in the second half of the season.

Meanwhile, Castle (Nathan Fillion) and Beckett (Stana Katic) will have their own personal matters with which to attend. The TVLine report states that episode 15 is titled "Fidelis Ad Mortem," and centers on Beckett going back to the police academy where she originally trained.

Did Nathan Fillion & Stana Katic Win Big At People's Choice Awards?

Additionally, there is "fallout from the [preceding] L.A. episode, with regards to Castle's discovery about his missing time," co-showrunner Alexi Hawley told the publication.

Terence Paul Winter, a.k.a. Hawley's fellow showrunner, previously told Entertainment Weekly about the big episode involving Castle's missing time.

"We are going to conclude that missing time," he said. "We're going to find out exactly what happened. We know what happened those first two weeks, the other six weeks are still a mystery. We're going to find out what happens in episode 14."

Alexis (Molly Quinn) and Hayley (Toks Olagundoye) are goes on the big trip to Los Angeles.

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

Watch a promo trailer for the next episode of Castle below:

Tags: Castle television ABC