The queen who came in from the cold

It's 1961 and the Queen is headed to Italy aboard the Britannia, until murder gets in the way. When a witness claims to have seen a killing from the royal train, Her Majesty and her ever-capable aide Joan McGraw are on the case. Their investigation whisks them from palace corridors to the canals of Venice in a twisty tale of spies, secrets, and royal sleuthing.