John le Carré's The Circus: Losing Control #1

Every day, the intelligence agents of the Circus are enmeshed in high-stakes, high-wire acts that the average citizen would never notice. They protect Britain’s most sensitive secrets — and in modern Britain, secrets are everything. At the head of it all is Control: the all-powerful puppet master who decides who goes where, who does what, and sometimes, of necessity, who lives and who dies. But now, Control has vanished. He doesn’t show up at the office. He misses his meetings. He won’t — or can’t — answer his phone. He is, simply, nowhere. Control’s assistant Maggie is the only one who knows he’s gone, and with an imminent and critical mission in Vienna, the clock is ticking. Maggie knows every protocol, every password, and every operative — but whether something has happened to Control or whether this is part of his plan, she has no idea. Either way, she can’t trust anyone with the knowledge of his absence. Can she even trust him. Secrets within the Circus have a way of coming unraveled, and Maggie will have to act fast... or risk the walls tumbling down around her.