The season finale of "Castle" is expected to focus on "the mythology" of Kate (Stana Katic) and Rick's (Nathan Fillion) relationship.

Further being billed as "compelling, high-stakes, story-telling, Episode 22 of Season 7 will mark No. 150 for the program overall.

"Obviously, the 150th episode is a milestone for the show, but it also directly precedes the season finale," show runner David Arman recently told TvLine.com. "At this point, we intend Episode 22 to be a buoyant, classic episode of 'Castle,' while [the finale] will focus on compelling, high-stakes story-telling surrounding Castle and Beckett mythology."

The episode is also expected to delve into the Season 6 disappearance of Castle on his wedding day. Some of this season's initial episodes touched upon the mystery, but recent shows have seemingly put that plotline on the back burner.

Show creators have yet to publicly reveal if the ABC aired show will be returning to the network for a new season next year, though it continues to remain popular among its base audience.

Revolving around the intense relationship between mystery writer Castle and NYPD detective Beckett, the show also stars Jon Huertas as Det. Javier "Javi" Esposito, Seamus Dever as Det. Kevin Ryan, Ruben Santiago-Hudson as Cap. Roy Montgomery, Tamala Jones as Lanie Parish and Susan Sullivan as Martha Rodgers.

Earlier this year, TVLine.com reported it is more than "likely" the show will be renewed for an eighth season, even though Fillion and Katic's current contracts are set to expire at the end of the season.

"We love 'Castle,' we love those two and we want to see 'Castle' on the air for many years to come," ABC president Paul Lee told TVLine. "It will be coming back," he added.