Young Keepers Cora and Jax are looking forward to the Moonlight Party raft race - with their friend Trix's help, they have built a special raft. But at the same time they are beginning to wonder if they'll ever become fully trained Keepers, despite all their rewilding efforts. Then, after an exciting expedition to build a bug hotel and salvage supermarket food waste, they come across a young otter stranded in the stream. Suddenly the raft has a much more important role than Cora ever imagined.