‘You think that was Biggs’s blood at the dump? Not Ruthven’s?’

‘Biggs went missing more recently than Ruthven, and the blood wasn’t old. Not fresh, but not old.’

‘And why December nine?’

‘Those splotches of blood weren’t random spatter. He was marking specific dates. The last one was the ninth of December. Tomorrow.’

A beat.

‘Okay,’ Thistle says. ‘So Biggs pricked his own finger and decided to write with his own blood, rather than doing something more obvious and less dramatic.’

‘Like what?’

‘Like using the whiteboard marker right under the calendar.’

‘We wouldn’t have paid attention to that,’ I say. ‘Random dots of marker on a wall planner.’

‘We would have, if he added a message explaining what they meant.’

‘His captors would have seen a message when they moved him. They would have cleaned it up. Blood was the only way to get our attention without getting theirs.’

‘So what happens tomorrow?’

‘I don’t know,’ I say. ‘But whatever it is, it happened at least eleven times before. There was a date marked on each month. January ninth, February thirteenth, March nineteenth—’

‘I have the dates. I took a picture. So if we work out what happened on all of those days …’

‘Then we can guess what’s supposed to happen tomorrow.’

‘I don’t even know what to look for,’ Thistle says.

‘Get Vasquez on it. Maybe he can use software to look for similarities.’

‘We don’t have much time. I’ll call him now.’ A pause. ‘Good work, Blake.’ The line goes dead.

A flutter of pride, but also guilt, as I look down at Biggs. Thistle wouldn’t be congratulating me if she knew whose finger had ‘tipped’ me off.

She’s more right than she knows—we don’t have much time. I need to solve this case quickly so I can stop working it before Warner kills me. Which means I can’t just wait around for Vasquez to find an answer. I need to go back to where I first found Biggs. If the killer dumped his body there, then maybe I’ll find Ruthven there too.

Texas has a drive-through culture, and I’m not immune to it. I can’t resist carving some more off Biggs to eat on the way. As I slide the knife under his pectoral muscle, I see something strange beneath his ribs.

I have to crack them with a hammer to get to it. When I finally pull it out and wash the gore off, I don’t recognise it. A little silver bulb, topped by wires contained in transparent plastic.

A pacemaker—it must be. Which turns this whole thing upside down.