For a moment, the sound confused her—she had not been asleep, precisely, but had entered a fugue state in which memories and plans collided, throwing sparks off each other—and she jerked upright, banging her head against the cistern. An image of her sister popped and vanished as the cubicle light flickered on, followed by the other bulbs in the lavatory. Her heart pounded. Someone would come. But nobody did, and after a moment Maggie unfolded her limbs, which were creaky with cold, and tried to rub life into them.

Pins and needles assaulted her fingers. She did not feel like an agent on a mission. She felt like a young woman up past bedtime, who wanted only to crawl beneath some covers and find warmth.

“What do I do now, Harvey?” she whispered.

It would have been nice if he’d been there, offering an answer. But it was up to her now. She was on her own.

Because it didn’t matter—because the lights had blinked on anyway—before making her way out of the cubicle, she raised the toilet lid, pulled down her jeans and pants, and used it for the purpose for which it was intended. Then she rearranged her clothing, closed the lid, and had her hand on the handle before she caught herself—that would be all she needed, to send a watery alarm cascading through the building. She imagined security guards stomping up and down the stairwells, crashing into the lavatories on each floor, throwing open doors, looking for the culprit.

“Maggie, Maggie,” she murmured to herself.

When her heart rate was normal she unlocked her cubicle and tiptoed to the door and opened it and peered out.

The corridor was in darkness. The motion sensors were sleepy, and wouldn’t kick in until she stepped outside. Even then they allowed a second or two’s grace, as if they needed convincing that they weren’t rousing themselves for someone of no consequence. For a mouse, creeping its night-time way along an empty hall.

Rather than a spy. An agent on a mission.

“Trying not to make the lights come on will only stress you out,” Harvey had said. “It can’t be done. You have to move to get where you need to be, and the sensors will do the rest. So don’t worry about them. You can’t control the things you can’t control.”

It was nice that he was confident she could control the other things.

“Maggie, Maggie,” she chided herself again. Here was the equation: if the lights were off, the guard wasn’t on this floor. And if he wasn’t on this floor, he wouldn’t see the lights coming on.

Which meant it was safe to step out into the corridor.

But before she could do so the lights flickered and the door to the lobby clicked shut, and then—loud as a lion—she could hear the breathy whistling of the security guard as he rounded the corner, heading her way.