On April 12, 1966, a family picnic in America's first national park turned into one of the most baffling missing persons cases in American history. Eight-year-old Dennis Johnson was visiting Yellowstone with his parents William and Betty and his three sisters when his seven-year-old sister Mary wandered off. Dennis and his father split up to search for her. William found Mary quickly, but when he returned to the Cascade Picnic Area, Dennis had vanished without a trace.

What followed was one of the most intensive search operations in Yellowstone's history – spanning 100 square miles, employing helicopters, bloodhounds, and dozens of searchers. Despite three weeks of exhaustive efforts costing over $14,000 (equivalent to more than $100,000 today), not a single clue was found. No footprints. No clothing. No evidence whatsoever. Fifty-eight years later, Dennis Johnson remains missing, his fate unknown.

In This Episode

• The detailed timeline of April 12, 1966, and how a moment's separation led to decades of mystery
• Why the search for Dennis was particularly challenging, and the technical aspects of a 1960s-era wilderness search
• The baffling behavior of bloodhounds that couldn't pick up any scent trail
• Five leading theories of what might have happened to Dennis, and why none can fully explain his complete disappearance
• How the Johnson family turned to a psychic in their desperate search for answers
• What makes wilderness disappearances unique, and the concept of "ambiguous loss"
• The statistical context: how rare cases like Dennis's are compared to millions of safe Yellowstone visits
• How the case has informed modern search and rescue techniques and park safety protocols