History and Mystery Reads

Rating: 6/10

• Accuracy: Good on the Boulogne camp of 1805, Napoleon’s planned invasion of Britain, and Fouché’s police.
• Plot: Sentries are being murdered in Napoleon’s invasion camp, and a British spy is set to catch the killer by the French themselves.
• Clues: Clever in places, but buried under espionage twists.
• Reveal: Surprising but convoluted, relying on explanations that arrive too fast.

In 1805 Napoleon’s Grande Armée is massed at Boulogne, preparing to invade England. The camp is shaken by a series of murders: sentries are being stabbed at night by an unseen killer. The French suspect a British agent. Fouché, the minister of police, assigns the hunt to Alan Hepburn, a British spy whose true loyalty Fouché may already suspect.

It is a delightfully perverse premise. Hepburn must track the killer while protecting his cover and his wife, who is drawn into the intrigue. The camp, with its fog, invasion barges and constant surveillance, is well drawn.

Carr’s research shows in the military and political details, and Fouché, a master manipulator, is the highlight. The sense that everyone is watching everyone gives the book an agreeable paranoia.

But the plot becomes overloaded. Double-crosses, romantic misunderstandings and multiple suspects crowd out the central murders. Hepburn spends much of the book being outwitted, and tension sometimes tips into confusion.

The solution surprises, but it depends on a string of revelations that come too quickly to feel earned. Readers who prize Carr’s fair-play puzzles may feel short-changed.

The 6 reflects a strong idea and a vivid setting undermined by an overcomplicated plot. It still entertains, especially anyone interested in the Napoleonic era, but it is not Carr at his best.