The only noise in Hardy’s world was the steady slush and suck of the water curling behind him as he walked around and around, alone in the circular pool.

Pico Morales had called around seven to ask if he felt like doing some walking. When Pico called, it meant that some fishing boat had landed a great white shark and had contacted the Aquarium. The sharks bred just off the Farallons, and the Steinhart – or Pico, its curator -wanted a live one badly. The problem was that the beasts became so traumatised, or wounded, or both, after they were caught, that none survived. Too exhausted to move on their own, they had to be walked through the water so that they could breathe.

It was Hardy’s third and last hour-long shift tonight. He’d been spelled by a couple of other volunteers earlier, and Pico was due any minute, so Hardy just walked, unthinking, putting down one foot after another, dragging and pulling the half-dead monster along with him.

On his first break, he’d stripped off his wetsuit, changed and walked over to the Little Shamrock for a Guinness or two. Hardy’s brother-in-law, Frannie’s brother Moses McGuire had been off. Lynne Leish was working her normal Sunday shift behind the rail, and Hardy had taken his drink to the back and sat, speaking to no one.

On his next break, he’d gone out and climbed a fence into the Japanese Tea Garden. Sitting on a footbridge, he listened to the orchestrated trickle of the artificial stream that flowed between the bonsais and pagodas. The fog had been in, and it hadn’t made the evening any warmer.

Hardy wasn’t paying attention when Pico came in. Suddenly there he was at the side of the pool, his huge bulk straining his wetsuit to its limit. Pico had a large black drooping moustache that got wet every time he brought the steaming cup to his lips. ‘Hey, Diz.’