Twelve-year-old Bibi Blundermuss is terrified of trees. Being around them makes her dizzy and sick to her stomach-even comatose. So, when her only to chance to find her missing parents means climbing a magic tree in the forest near her home, she almost doesn't take it.

When Bibi grits her teeth and scales the trunk, the tree grows-so violently that she and her cat Eek are catapulted into another world. Here, she befriends a herd of elk, on the run from a pack of vicious white lions. And she discovers, to her amazement, that her mother is a witch who has been protecting the elk with a poison flower spell, which keeps the lions away.

Yet the longer Bibi stays in the world of the elk and lions, the less sure she is that her mother is truly on the elks' side-or even on Bibi's side. In the end, a dangerous journey into the lions' lair and a reunion with both parents uncovers a secret that changes Bibi's life forever. Drawn into an epic snowbound battle against an army of zombie trees, she must face her greatest fear to discover her greatest power.