The Portal Keeper by David A. Robertson

Eli and Morgan experience life-changing revelations in this new adventure in the award-winning, Narnia-inspired Indigenous middle-grade fantasy series.
While exploring World's End, an area in Aski they've just discovered, Morgan and Emily delight in their developing relationship, while Eli struggles to understand his new-found power: the ability to locate a portal. A shocking turn of events leads them to a new village, Ministik, where the animal beings who live there are going missing. Horrified to discover who is responsible, the children vow to help and turn to friends, old and new. But it's getting harder and harder to keep the two worlds separate, especially when details of a traditional legend change everything. Forever.