Fifteen-year-old Peak Marcello is invited to participate in an "International Peace Ascent" in the Hindu Kush, with a team made up of under-eighteen-year-old climbers from around the world--but from the first something seems wrong, so when the group is attacked, and most of the climbers are either killed or kidnapped, Peak finds himself caught up in a struggle to survive, shadowed by the Shen, a mysterious snow leopard.

The magic tree house is back with a message from Morgan le Fay telling Jack and Annie to seek out "The Gray Ghost" and listen to her story, and immediately they are whisked away to Nepal where they meet Tenzin, a climber who has recently lost his family, and who takes them up the mountain to meet a snow leopard and renew himself.