Before dawn on April 4, 1994, Abigail Alling and Mark Van Thillo slipped across the foothills of Arizona's Santa Catalina Mountains. They made their way to a looming monument of geodesic domes and pyramids known as Biosphere 2. The 3-acre complex contained a miniature rainforest, a mangrove, a desert and a coral reef — along with seven people who had been sealed inside for a month.

Alling and Van Thillo had recently emerged from a two-year stay in Biosphere 2. Later, after they were arrested, they told reporters that they feared for the safety of the people inside. They were