You can’t teach an old dog new tricks. The person who coined that phrase had clearly never met Anna Vincent. Or attended an Internet for Seniors class at the Chappaqua public library.

Mr. McGrath’s death hadn’t come as a blow to Anna. She’d never liked him. And in fact, once the dust had settled and she’d had the chance to reflect on it, she had to admit she’d found the whole episode very satisfying. It had proved that even after lying dormant for all those years, her instincts and her skills were just as sharp as ever. She hadn’t frozen when she overheard the conversation between Mr. McGrath and his partner about getting the brownstone cleared out. She hadn’t panicked. Instead her training had kicked in. Instantly. She’d dosed the tea just right despite not having handled K-2 since the poisons course she attended at Laboratory 12, more than forty years ago. She delivered the drink without arousing suspicion. Had the presence of mind to remove the cup and destroy it off-site, later. And she’d smashed up the study so comprehensively that the police hadn’t doubted for a second that a man—like Alex Pardew—must have done it.

With the target of her surveillance out of the picture, Anna’s thoughts turned to Russia again. She seriously contemplated going back. She’d had no contact with her handler for years, so she no longer felt the need to seek his permission. But everything she read suggested that the corridors of power were crawling with oligarchs now, who were more interested in collecting expensive apartments in foreign capital cities and buying Premier League soccer teams than in fighting for the worldwide emancipation of the proletariat. She also found that she liked the house a whole lot better now that she lived in it on her own. What she needed was a way to continue her mission, but without having to leave. The library provided that. The library, plus a new computer and a fast Internet connection. Although really she felt the new technology made the job too easy. When she began her training, back in Leningrad, changing your identity was a complicated business. Now you could create an entirely new persona with a few clicks of the mouse. In her formative days, you could only be in one place at any given time. And it used to be dangerous to operate in the same city using more than one cover story. But now you could just open multiple windows on your screen and be anyone, anywhere.

After six months Anna had cut back on her initial enthusiastic overproliferation and settled on just becoming three other people. Most of the time she was Sophie, a mild-mannered teacher from Detroit who was dedicated to educating teenagers about the true meaning of socialism. The movement had gained some popularity—in name, at least—in the country over the last couple of years, but it was clear to Anna that the spoiled American brats who thought that posting trite memes online was radical behavior actually had no concept of its underlying principles. That wasn’t their fault, she told herself. They’d been raised in a degenerate environment, starved of the oxygen of truth, and were in desperate need of guidance from someone who did understand the true struggle. She also enjoyed the role of Scar, a guru of activism who operated exclusively in private groups, where he could be more forthright in encouraging workers to organize and resist. And when she was feeling playful, Kali would take to Facebook and Twitter where she could bait fascists and ridicule their brainwashed mantras to her heart’s content.

When she put the three strands together Anna was more satisfied than at any time since she’d left Leningrad. She had a good routine. She felt like she was making a contribution. And she enjoyed the poetic justice of taking corporate America’s profit-hungry products and using them to hasten its own demise. The disastrous events of the world may have pushed utopia further into the distance, but that was no reason to give up on trying to reach it.

It was a shock when Paul appeared on her doorstep. She worried that it wouldn’t be safe to continue her work if he wanted to live in the house with her. It wouldn’t have been an insurmountable problem—she’d chosen a laptop because it was portable, and all her passwords were safely memorized so she could easily rebuild her profiles even if it became necessary to ditch and destroy the computer—but she was still relieved when Paul opted to stay at a hotel in the city. She worried again when he found out about the brownstone and decided to move in there. Then she calmed herself down. The alert level was no higher than amber, she figured. There was no way Paul could know the significance of the house. About what was hidden in the walls. It would make sense to be extra vigilant, though, so Anna contacted the person who’d been watching the house for her since Mr. McGrath had bought it. She ordered an increase in the frequency of the reports from weekly to daily. There was a commensurate increase in the fee she had to pay, but this was America. What else could she expect? And anyway, it was worth spending a little more for her peace of mind.

The new message schedule took effect the day Paul moved into the brownstone. Every day, within five minutes of 5:00 P.M., Anna received an email: Are you free for dinner tomorrow, say around 7:00 P.M.? That meant there was nothing to report, so Anna just sent back her confirmation of receipt: Sorry, I’m busy all week. Then one Saturday morning Anna received a different message: A slot just opened in my diary. Are you free for coffee right away? That was an alarm. The most urgent kind. Anna replied: What changed at your end? A moment later an email arrived with a photograph attached. One snapped with a cellphone. There was no skill involved with it, unlike the ones Anna used to take. But she couldn’t question its significance. It showed a van. Parked outside the brownstone. Navy blue, with a gold shield logo. And Paul letting two men—one with tools, one carrying a clipboard—into the house.

A picture like that could mean only one thing.

It was finally time for Anna to run.