A diplomatic scandal. An escape over the rooftops. Charges of treason. Just a normal night out for Regency London's most elegant spies Mélanie and Malcolm Rannoch.     For aristocratic former spies Mélanie and Malcolm Rannoch, an attempt to steal incriminating documents is a normal evening out in Mayfair. The Napoleonic Wars taught the Rannochs to be prepared for the unexpected. But it seems they've acquired a lethal new enemy who not only snagged the papers ahead of them, but has been amassing information to blackmail them and their dearest friends.     Suddenly their mission turns far more dangerous. They're no longer just working to avert a diplomatic scandal. They are trying to protect those closest to them from arrest and imprisonment. Mélanie and Malcolm hatch a dangerous plot to outwit their enemy on a royal night at the opera, with the king in attendance. But in candlelit salons it's difficult to tell allies from enemies. And if they fail, it is the Rannochs themselves who could be facing charges of treason...