The Season 7 finale of “Castle” will air Monday amid uncertainty about the popular ABC series’ future. Despite ongoing contract negotiations and doubt surrounding star Stana Katic’s return next fall, the show must go on as episode 23, “Hollander’s Woods,” gives fans a peek into Castle’s (Nathan Fillion) mysterious past.

According to the synopsis for the new episode, Castle will be rattled when a body found in the woods reminds him of a traumatic event from his childhood. In fact, it might force him to recall the reason he became a mystery writer in the first place. The promo for the episode provides a glimpse at the dark memory as an 11-year-old Castle is thrown against a tree by a hooded, masked man. Beckett (Katic) tells her husband, “You’ve made this killer your personal boogeyman.” What is the connection to the new case?

Watch the promo for the Season 7 finale below:

Meanwhile, the synopsis reveals that Beckett will face a turning point in her life. With Katic’s future on the show up in the air, the writers were forced to leave her character's season-ending arc a bit open-ended.

“As she’s settled into the relationship with Castle, [there’s] this growing dissatisfaction with where she is in her career, and we’ve been arcing toward something at the end of the season," executive producer Andrew Marlowe told Entertainment Weekly. "Some of the stuff we’ve been dealing with really comes to fruition in this last episode in a very unexpected way that we think will be a great springboard into some really compelling storytelling next year.” Marlowe added that the ending was designed to provide some closure in case Katic – or the show itself – does not return.

As it stands, ABC has renewed “Castle” for Season 8 next fall, with “State of Affairs” creator Alexi Hawley and “Castle” veteran Terence Paul Winter set to take over showrunner duties from outgoing executive producer David Amann. Fillion has signed for another season.

The Season 7 finale of “Castle” will air Monday at 10 p.m. EDT on ABC. How will it all end? Fans will have to wait to find out.