It's the mid-summer fayre in the Drift, the biggest event of the year for the animals who live there. There's a surprise visitor for the friends which causes great excitement. However, the thrill of the fayre is gone the following morning with the discovery of numerous dead fish in the river, was this an accident or has someone done this? Rollie and Toby seek out Monty, Toby's uncle, for help, this leads them to the mysterious...