The beach was a shimmering golden crescent gilding a mile or so of bushy wild-land through which a dozen narrow tracks threaded criss-cross down to the sand. It was late June and the first week of real summer had arrived. A cacophony of yelling and laughter churned the air, mingling with seagull cries and the slow constant thrum of the surf. Children hunkered in groups of two or three around heaps of sand which they were trying to cajole, by hand and bucket, into the shapes of castles and forts. Suddenly a shout of dismay rose over the general hubbub and a boy flung a clod of sand after the black labrador that had run through his sandcastle. The dog carried on heedless, sprinting for the water. The boy followed. Together they waded past the first line of shallow waves and greeted a girl who had been standing still, looking out at the hazy horizon. ‘Tike destroyed my sandcastle,’ the boy complained. ‘Good dog,’ said the girl. Tike paddled noisily between them. The boy started to ask if they should build a new sandcastle, but the girl shrieked and pushed him backwards. He fell as she ran-hopped past him. He scrambled after her. ‘What?’ he asked. The girl pointed at a pale, solid form in the nearest wave, a translucent blob that grew and shrank in lazy undulations. Tike had spotted it too and was swimming towards it. ‘Tike,’ shouted the girl. ‘No, Tike, leave it alone.’ The dog ignored her. As the plate-sized bell of the jellyfish pulsed, its tentacles convulsed in slow spirals around it. The children shouted and waved. Tike was well within reach of the tentacles now, only avoiding them by blind luck. The girl picked up a seaweed root, shouted ‘Tike’ at the top of her voice, and flung the slick dark branch in the very opposite direction of the jellyfish. Tike watched it fly, thrashed to a stop, and paddled energetically after it. The children slumped down on the sand and waited for Tike to return the stick. Then they would take him to their parents further up the beach and perhaps see if there were any crisps in the picnic box.