Columbine: The Waterfolk in this rather terrifying story are tiny creatures, barely seeable by the humans they call “Paddlefeet”. They are a translucent blue, and resemble mermaids in having tails, though they have only one eye and are telepathic. They live behind a waterfall in a river pool and have a very ceremonial culture based around the sacred circle. “The pebbles must be arranged in a small circle on the rock floor…. They now sit magically defining the truth, the space which is within, the O.”

They are naturally wary of the beings who “invade suddenly and without warning, churning the water with their vast, thrashing limbs and giant paddle feet”. However, once long ago one of them was helped by a Paddlefoot boy, and it is this memory which leads them to seek help when the rain fails and the river dries up. That boy, Tom, is now a very old man, still living by the river and cherishing his memory of the time he saw a marvellous little creature. He is dismayed by the change in the river, every year a little lower, until at last the waterfall is a mere trickle. He has kept the secret all these years but now he considers sharing it with a young girl, Jo, who visits the river with her friends. She once caught a glimpse: “something small, something deep blue, something which flashed upstream against the flow of the water” — but by the time she becomes fully aware, it is almost too late.

The slow drying up of the river bed from the point of view of the Waterfolk is sensitively, almost agonizingly told. The elders are fatalistic at the passing of their world, but the young Axos has a Dream of the Future, of change. He says: “There is, outside our knowing, something more to know.” He and his friend Odol are determined to hold on to hope, even after “the smoke-like streak of the other Waterfolk have thinned to fine gossamer threads before vanishing completely.” Only they and two even tinier babies are left. Jo at last realizes what she must do, though her clumsy and makeshift methods add to the Waterfolks’ distress for a while.

The book ends with the Waterfolk transplanted to a Welsh mountain stream; a muted ending, as the tribe is so diminished and the stream is not so rich in life as the river once was, but for them a new strange beginning. The book has a powerful sense of the extreme fragility of life, and shows the great chasm between the experiences of the Waterfolk and of the Paddlefeet, as this great tragedy unfolds while the ordinary daily human life goes on unaware.