A dangerous step-brother ... a letter from a Venice ... a secret key ... and London's most fashionable portraitist. Dark doings and deceptions surround an unexpected legacy ... and an equally unexpected love story.

Upon learning that his step-sister, Mariella Talbot, is the beneficiary of a surprise inheritance, Sir Jerome Farrell decides to seize it for himself.
Already struggling to thwart her step-brother's other wicked intentions, Mariella realises two things; to claim the Montesoro legacy, Jerome must make a lengthy journey ... but without a certain item in her possession, he will return empty-handed.
Successful, sought-after and contemplating marriage to a lovely, young widow, Leo Brandon's commission to paint Charlotte Farrell, takes him to Surrey for three days. Had he known in advance how those days would re-arrange his life, he might have made the catastrophic mistake of staying in London.
Meanwhile, the agents of M Section are interested in Sir Jerome for reasons of their own ... and, unlike Mariella, are less than delighted when he leaves the country.