Former CIA analyst, Jack Ryan is on holiday in London with his family. On his way to meet them he foils an assassination attempt on a member of the Royal Family by the IRA, killing one of the attackers in the process.
Jack gets drawn back into the CIA when he and his family then become targets for a renegade IRA squad led by the brother of the IRA-man killed in London. Annette (Polly Walker) is an English IRA assassin who takes part in the operation: she adopts a red-headed disguise to pass undetected in London and to kill a member of another IRA faction
Tom Clancy novels are low on plausibility and this is no different – why would a killer remove their disguise at the scene of their crime?