ALL KARA WAS ABLE TO glean from eavesdropping at the cathedral was that, yes, the Twelve were here for three weeks, but everything about their stay was top-secret; hardly anyone in the Church offices knew more than that. So, after some research on the internet, Alex had made an appointment at an insurance company based on the Torre Mayor’s fifty-fourth floor – one floor from its top.

He’d taken the Metro, then walked. The Torre Mayor was the tallest building in Mexico, and looked it, soaring up over its surroundings. Approaching from the Paseo de la Reforma, Alex saw that the half-cylinder of green glass was only the front of the building – its back was a tan, rectangular slab. The entrance – a graceful arch, several storeys high – mirrored the half-moon shape at the building’s top; slim grey columns marched across it.

Going in, Alex had found himself in a lobby with a slanting glass ceiling overhead. Like Kara had said, there were scanners in place; employees passing through briefly touched their passes to them. “Richard Singer,” said Alex to a receptionist at a glass-topped desk. “I’ve got an appointment with Prima Life.”

No flicker of suspicion; the woman made a phone call to verify, then pushed a clipboard at him to sign in. Alex took the temporary pass she gave him and went through the scanners. As he did, he noted the several cameras that were tucked away in various corners, watching his every move.

Going online, the team had found out quite a few things about the Torre Mayor: apart from being extremely secure, it was the most earthquake-resistant building in the world – it could withstand up to a level nine on the Richter scale. There’d been no floor plans to be found though, not anywhere online. But while it wasn’t mentioned on the Torre Mayor’s website, they’d found a reference on someone’s blog that said its top floor – right under that slanted half-moon – had high-security VIP suites and meeting rooms.

In the elevator there’d been another camera, and an attendant who asked him what floor he wanted. “Fifty-five,” said Alex, just to see what would happen.

The man’s eyebrows had knitted together as he checked Alex’s pass. “Sorry, Señor – you need a special card for that.”

Alex feigned confusion, taking out the piece of paper from his pocket where he’d scribbled down the details of the meeting. “Sorry, I meant fifty-four,” he said, putting it away again. As the elevator hummed upwards, he took in the keyhole beside the button for the highest floor. Okay, so what would happen if the team overpowered the attendant and got the key? But, remembering what they’d found out so far, he knew: computers ran everything here; the security staff would just stop the elevator.