In Illegal Action, the tireless and brilliant MI5 agent Liz Carlyle returns in another suspenseful, action-packed espionage story. Author Stella Rimington was an MI5 agent and the first woman to reach the position of Director General of the organization. Stella's notoriety as a secret agent lends credibility to the thriller, part of the series that is one of the most successful in English crime fiction. Liz and Peggy Kinsolving, her right-hand woman, are transferred to counterintelligence—a sector that has long been in the spotlight but, after the first terrorist attacks, has become considerably smaller. However, Liz soon discovers that there are more spies circulating in London than during the Cold War. Their target now is the influential Russian oligarchs opposed to Vladimir Putin's government who have migrated to the city to spend their fortune. Upon learning of a possible Moscow government plot to assassinate one of these powerful oligarchs, Nikita Brunovsky, Liz quickly finds a way to get closer to the Russian to monitor his every move. The investigation takes a different turn when Kinsolving discovers that an Illegal—someone operating under a false identity in a foreign country—is operating in London. Liz, infiltrated in Brunovsky's home under the false identity of an art history researcher, suspects that Brunovsky's traitor is also the Illegal MI5 is seeking. But the situation becomes more complicated when the agent herself becomes a target.