It is 2016 and a bullet-holed French army jacket of Crimean War vintage and a soldier's 1854 letter mentioning his comrade's murder arouses the interest of Anna and Martin Price. They follow the path of a mysterious agent of the Russian Orthodox Church from a ruined monastery in Inkerman to Marseilles and from there to Paris where they initially lose sight of him. Access to the records of Les Invalides enables them to once more pick up his trail only to find that he died in an accident at a North London pub in 1887.

While investigating the Russian agent, the unexpected appearance in Sarony of Martin's ex-wife Yvonne provokes a confrontation at Auberge Fleurie between Martin and Gerard, Yvonne's companion. Martin's threat to kill the man results in suspicion falling on him when Gerard is murdered in Dijon a few hours later. Help requested in Yvonne's phone call to Martin is vetoed by Anna who fears that her husband's ex-wife is involved in a drug distribution racket. Within forty-eight hours Yvonne's body is pulled from a Dijon lake. Much to Anna's displeasure, Martin sets out to find her killer and following their visit to London, the couple are forced to accept the unlikely evidence of a link existing between the soldier's murder in 1854 murder and Yvonne's murder in 2016.

They are not the only people interested in what their London visit uncovered and Anna finds herself cornered by a vengeful psychopath.