Tracker Sets The Stage For Jensen Ackles' Return As Russell — What Did Colter Just Learn About Their Father?

Sunday's "Tracker" didn't deliver answers about Colter Shaw's father... but it did drop a few tantalizing new clues.

After tracking down the elusive Buck Avery (Michael O'Neill), Colter wasted no time getting to the point: he was looking for anything that might explain what his father, Ashton Shaw, was doing in the Alaskan wilderness in the months leading up to his death. Buck, initially cagey, eventually invited Colter inside and confirmed that he did, in fact, know Ashton.

From there, the conversation took a turn.

Colter shared what he had pieced together from his father's journals: Ashton's abrupt exit from academia, the move to an isolated compound, and his apparent involvement with something called the Chronostasis Institute. That name rang a bell for Buck, who revealed that his family once leased land in the area to government contractors — land that housed a now-defunct, highly secretive research facility.

According to Buck, the operation was allegedly funded by DARPA and dabbled in everything from weather experiments to "other weirder stuff." But whatever they were working on didn't end cleanly. Buck recalled an "accident" that prompted a sudden shutdown, with the entire operation disappearing "like it never existed."

That's where things got even murkier.

Buck pointed Colter toward a key figure: Dr. Serena Jukic, a researcher who was deeply involved in the project and might have known what really happened. She had mentioned the accident in passing, Buck said, but never elaborated, then vanished not long after the facility was shuttered.

Buck confirmed that Ashton had been in the area when the accident occurred, though what he was doing remained anyone's guess.

The hour closed on a tease that set up Season 3's endgame — and Jensen Ackles' previously announced return in the Sunday, May 24 finale.

Colter reached out to his brother Russell, leaving a voicemail that laid it all out: their father had been tied to a deep government cover-up, and Colter now had a name. If Russell was interested, it was time to help track Dr. Jukic down.

The logline for the finale, titled "The Best Ones," read simply as follows: "Colter and Russell search for a victim of a nefarious research project." Do you think the finale will finally deliver answers, and put this long-running family mystery to rest?