‘Where would you spend the Dry if you were a frog?’

‘How would I get in? Hop from rung to rung?’

Tom’s face materialises, pale grey on black, and they float in silence on their backs, side by side, for a time.

‘Where is the ladder?’ Tom asks.

‘Had enough?’

‘I’m feeling a bit wonky. I might throw up.’

‘Don’t expect a goodnight kiss.’ Kenny peers up at the high rim of the tank, an ill-defined margin between the total blackness of the interior and the star-pricked darkness of the night sky. A first, slight shiver: he, too, has no idea which side the ladder is on.

‘I’ll feel around the edge.’ He kicks himself to the nearest corner of the tank, finding it by touch, then sets off, sidestroke, trailing one hand along the slimy wall. A faint premonition of tiredness enters the muscles of his upper arms, a slight heaviness, or resistance to movement; after the second corner he rolls onto his back and propels himself using his legs alone, long lazy frog-kicks.

‘Where are you?’ Tom’s voice is some distance away, but loudly resonant, rebounding between walls.

‘On the last wall. Can’t find it.’ As he floats, resting, the obvious strikes him. ‘It’s the end of the Dry. The water level is below the bottom rung.’

‘So what do we fucking do? Wait for the monsoon to float us up?’

They tread water in silence, listening. The thunder is no more than a distant grumble, a faint tremor in the water. Or is the tremor internal, another shiver? Kenny earnt his Lifesaving Certificate years before, half rite-of-passage, half trial-by-ordeal. He feels at home in the water – but the weary ache in his upper arms is growing.

‘I’m not feeling good about this,’ Tom is saying somewhere.

‘We’ll be fine. Just float till daybreak.’

‘Then what? No-one will find us.’

‘We can yell.’

Silence, then Tom again: ‘I am going to throw up.’

‘Hold onto it, for Christ’s sake.’

The noise of retching is close at hand.

‘Choice,’ Kenny mutters. ‘Fucking choice.’ Lying on his back, half sunk in the huge mattress of water, he scrutinises the tops of the walls. Shreds of cloud move slowly across the starry square of the night sky, as if on some darkened movie screen. ‘You okay?’

Tom seems to spit his answer out, as if the words are the last vestige of vomit. ‘Fucking wonderful.’

Kenny floats on, trying to keep calm, to think things through, but Tom won’t leave him alone. ‘How did we get into this fucking mess?’

‘You jumped, remember?’

‘You didn’t fucking stop me!’

‘So it’s my fault?’ Silence in the great vault, till a thought strikes Kenny. ‘Which side is the ladder on?’

‘The school side.’

He feels a stirring of anger towards his friend. ‘I know that, dickhead. Which side? North?’

‘North-west.’

‘Then the ladder is on the far wall. Look at the clouds. The weather is coming from the north-west.’

‘So?’

‘Maybe I can give you a leg up. Try and grab it.’