Darting through the water, the tiny creature feels a vast shadow and sees gigantic thrashing limbs: a Paddlefoot! Peering into the depths from up above, the girl glimpses a flash of blue and a sequinned tail. Surely she must be dreaming?

Little does Jo know what she has spotted one of the Waterfolk who have made their home behind the waterfall. Soon the destinies of Paddlefeet and Waterfolk are entwined as Jo and her friends, Fizz and Tash, battle to save the vulnerable river-dwellers before it' s too late, in the most exciting adventure of their lives.