Episode Overview
Challenger stumbles upon the remains of a World War I transport aircraft, only to be taken captive by its pilot, Lieutenant Drummond. Stranded for five years, Drummond has been safeguarding a shipment of iridium ingots that were pilfered from the Royal Navy. The iridium shocks Challenger, as it was originally earmarked for his covert wartime experiments. This revelation triggers memories of his own interrogation by MI5 agents concerning the theft on that fateful night five years ago. Upon returning to the Treehouse, Marguerite immediately identifies the iridium, recalling her own questioning by MI5 during the same incident. As the plot unfolds, unexpected connections emerge, suggesting that their gathering on the plateau might be far from coincidental.