Secret Headquarter: Challengers Mountain

Clipped from online: The Challengers are later semi-retired, their mountain a theme park, and their adventures disregarded as cooked-up articles in a tabloid, The Tattletale. The nearby town has renamed itself Challengerville, managing to thrive on the team's name. A cosmic entity, which prides itself as "the personification of all evil", influences the entity Multi-Man to blow up the mountain. The town is destroyed. Hundreds die, including, seemingly, Prof and June. The surviving Challengers are placed on trial, but eventually freed with the testimony of Superman. They are, however, ordered to disband.