They piled into the car. Mum let Jez sit in the front seat where he did all the talking with Alice leaning forward, face shining, laughing way too much. Mum parked on the verge and Jez commandeered the heavy basket. Greedy, too. Alice immediately fell in step with him and they walked ahead together, Jez with his long wavy ginger hair and stupid shorts, and Alice letting him put his freckly arm around her shoulder, smiling secret smiles. And Jumble was as bad, wagging his tail every time Jez looked at him.

Mum had chosen a Best Walk, a real special, where the stream and canal were side by side and there was a magic picnic place that only their family knew about. Why waste a Best Walk on a ginger stranger? Jez. Even his name was fake.

They dawdled, sitting on the lock wall, baking in the heat. And it was round the second bend that they saw them.

How beautiful swans are. They just floated, anchored in the middle of the swift current. One — father? mother? — headed the line, with five cygnets following on, and the second adult bringing up the rear; the perfect set-up. A happy family out on a beautiful summer day.

'That third cygnet,' said Mum after a minute. 'What's coming out of its beak?'

'Where? Oh yes — like garden twine or something.' Alice moved closer. They could all see it now. Not only the green string but also a large lump halfway down, grotesquely distending the cygnet's neck.

Lilly felt sick. 'What can we do?' she whispered, her mind whisking through suffocation, starvation, every painful death. She jumped to hear Jez's voice from somewhere near her knees. Crouching down, he had edged silently to the bank.

'We can't do anything,' he said. 'It'd need a vet, and soon.'

'But we can't get it to a vet.' Mum said what the three of them were thinking.

Jez turned his head to look at her. 'Oh, I'll catch it, if you don't think it's interfering.'

Just as he was, without even taking his smart trainers off, Jez walked down into the water and quietly approached the swans. The parent birds swam straight to meet him, putting their large strong bodies between this predator and their young. One of them reared up and lunged at Jez, wings spread at full stretch, hissing.

The swan hit Jez on the chest. He calmly gathered its body into his arms, hugging it almost, then turned it round and threw it gently downstream. Jez moved towards the youngsters, water up to his waist now, and picked up the injured one, folding its wings close against its body. He waded back to the bank.

'It's scared as well as hurt,' said Jez. He quietly covered the bird's eyes with his hand and then popped its head down the front of his T-shirt. 'Once it can't see it'll calm down.'

Lilly went with Mum. The RSPCA van when it came was complete with a swan straitjacket. They carried on to their picnic spot. Lilly lay on the rug, thinking, shivering her eyelashes to make the sunlight tremble pink and orange. She'd been wrong: it wasn't too hot for a picnic after all. She smiled up at the sky, eyes still closed. OK. Not a bad day, so far. She suddenly sat up, reached for the box of cakes and turned to Jez.

'D'you want one?' she asked. 'I make these for Alice — she likes them best.'