Bad actors

A key member of a Downing Street think-tank has disappeared without a trace. Claude Whelan, one-time First Desk of MI5's Regent's Park, is tasked with tracking her down. But the trail leads straight back to Regent's Park HQ itself, with its chief, Diana Taverner, as prime suspect. Meanwhile her Russian counterpart has unexpectedly shown up in London but has slipped under MI5's radar.