In Chicago Fire's Season 5 finale, things come to a head between Casey (Jesse Spencer) and Dawson (Monica Raymund) thanks to their new houseguest: Dawson's father, who's fallen on hard times after a divorce and some subsequent financial troubles.

"Gabby's father comes to stay ... and it's causing massive friction between Casey and Dawson," Spencer told TVGuide.com at the NBC upfronts Monday.

A catastrophic fire will no doubt force Casey and Dawson to re-focus on what's really important... but will it be too late?

"We have a pretty precarious incident scene that leaves the majority of Firehouse 51 in a building, in a structure fire," co-star Taylor Kinney says. "Dawson is outside, and the majority of us are stuck inside and doing our best to get out."

Finale Preview: See what's coming up on Chicago Fire and more

Chicago Fire co-creator Derek Haas previously told TVGuide.com that fans shouldn't be surprised if some characters' fates are left hanging in the balance as the show heads into its summer hiatus.

"It's going to be a harrowing one," Haas says of the call. "It's a dangerous job, and as we've shown on the show, anytime the bells go off, it could be dangerous for anyone. I will say no one's safe on this finale."

Check out the video to see what other hints Kinney and Spencer drop about the Season 5 finale.

Chicago Fire's Season 5 finale airs Tuesday at 10/9c on NBC.

Additional reporting by Alex Zalben