The murder of Sir Robert Bellingham, high-up in the Royal Navy, results in Emily Stearn told to infiltrate the Ivan Group, a team of female mercenaries based in London, who are out to get vital defense intelligence. Their leader, a Russian oligarch, already has a document outlining what the UK would do in the event of a nuclear attack but it is encoded. When Stearn's identity is uncovered, she is given 48 hours to steal the code key or her fiancé is dead.