‘They’re common enough around Darwin.’ Connor sounded preoccupied. ‘What were they up to? They’ve been back and forward, all over the place.’ The torch beam jerked down at the muddle of footprints across the guano-laden floor, then suddenly stilled on a hump parked on a ledge jutting from the side of the cave. ‘What’s that?’ Stepping towards it, he stumbled on something, swore and jerked the torch down to disclose a household brick. ‘What the hell’s that doing here?’

‘Connor!’ Tilly hissed. ‘It’s moving.’ She strained forward to see and, as the torch light returned, jerked back with a cry of alarm. ‘It’s a snake!’

‘Yes, I see. But it’s okay. It’s just a python – it’s come in after the bats, I expect.’

It was a big one, its body as thick as Tilly’s wrist, the pattern on it slipping through the yellow beam of light as it slid away. She stood rooted, but Connor was moving after it, his gaze on a dark object further back on the shelf.

‘Come and see,’ he called and reluctantly, her skin prickling against the touch of imaginary reptiles, Tilly stepped forward.

‘What is it?’

‘A box. A cage. I think this is where both that brick and the python came from. Look at the top. It’s hinged but there’s no latch – that’s what the brick was for, to hold the lid down, only the snake was stronger and must’ve shoved it off.’ Connor moved the torchlight along the shelf. ‘Yeah, the impressions are plain as print. That’s three, six, eight, I count, without this one. They’ve been using the cave as a depot, bringing them in until they had a full load to shift. Right under your noses, the cheeky bastards.’

‘What?’ Tilly demanded. ‘What are you talking about?’

‘Your wildlife traffickers,’ he said. ‘That’s who was here. See the marks where the other cages have stood? They were sneaking through in the night because they came to pick ’em up. The cockies and finches and lizards – whatever it was they had. Nine cages full. They’ll be long gone, and your wildlife with them, I’m afraid.’

Tilly stared at him. ‘But how could they keep them here? Birds, animals – they need food and water every day. Well, maybe snakes don’t . . . If they left them longer than overnight, there ought to be vehicles coming and going every day. There’s no point stealing them if you can’t keep them alive.’