I'm having a bit of trouble with a story/RP I'm working on. Casper, the protagonist, has been kidnapped, and his family and friends are trying to find him. Casper is being held in what was once a laboratory disguised as a ranger station in the Black Forest (the real one in Germany). Three years prior, Casper's son Jason was kidnapped by the lab/ranger station's previous inhabitants (scientists, of course) and experimented on before being rescued by his father, boyfriend and other friends. Currently the building is a base for a group of Nazis: Heinrich, their leader, wants revenge on Casper on behalf of his father, whom Casper's father had killed during WW2.
Now, Jason and his family have long since discovered that Casper has been kidnapped, but they have nothing but guesswork to lead them to the culprit. They are fairly sure of who did it and why, but they have no idea where Heinrich is keeping Casper. I want Jason to suspect that the old lab/ranger station is involved somehow, since he'd remember his own kidnapping and think it would make a good secret place for the Nazis to hide now that the scientists are gone. I just can't figure out how to portray his "gut instinct" as being believably correct. Help?