Having lost her husband in the Battle of Ligny, Lady Lydia Barrymore is determined to resume her work for the Foreign Office when her mourning period is over. She's spent a year solving puzzles and assembling dissected maps to maintain her skills. Her first assignment has her perplexed, though—do what she must to help a fellow operative recover his sanity. Although she finds the man rather beautiful, Sir Donald has also proved most annoying.

Newly knighted Adonis Truscott returned from the Continent with a tendency to get lost in his thoughts. His frequent episodes of...