A new entry in the Deception series, Defection, details the kidnapping of Rita Daveed, aka Harriet. The MSS needs to retrieve an audio SD card that will reveal the identity of Dragonfly, a Chinese sleeper agent embedded high-up in Vauxhall Cross. Defection is a story of treason, betrayal, and revenge. Three women with varying agendas clash over identifying the elusive spy known only as Dragonfly.

Before Rita is taken on orders from Yang Bo, the Director of the UFWD, she manages to leave behind a clue, a postcard from the Bowley Gallery in London, with a cryptic message scrawled on the back, "Find Harry!"

Yang Hu, an MSS agent and daughter of Yang Bo, decides she's had enough international intrigue. She makes the decision to defect to Great Britain.

Hu's get-out-of-China-alive card is her knowledge of who Dragonfly really is. She contacts Arty Pearl, Rita's boyfriend, telling him she knows where Rita is being held. In return, she wants Arty to inform Harry: MI6 has a mole.

The Quandary Team, now led by Harry, finds circumstantial evidence to suggest Alice May, the Special Assistant to the Chief of SIS, is Dragonfly. Sir William refuses to believe his longtime assistant is a spy. But he does authorize Harry to arrange Yang Hu's defection on the condition she reveals the true identity of the mole. Unfortunately, Sir William dies of a heart attack before Harry can make the arrangements. The new Acting Chief is a former Cabinet Minister and party hack, Thomas Burgundy-Smith. Burgundy-Smith rescinds the defection order, fires Harry, disbands Quandary, and promotes Alice May.

Rita escapes and begins to plot her revenge; Yang Hu puts her Plan B into action, and Alice May continues to disrupt the MI6 operations from her position of influence. Three women, three agendas, and one spy connive, maneuver, and manipulate the intelligence landscape for advantage, security, and revenge.