During a trip along the Thames, fate once again pulls Troy Allain, the wife of the famous Scotland Yard inspector, into the whirlpool of mysterious events. First, one of the passengers on the cruise steamer “Zodiac” is found dead, and then it turns out that the well-known art thief is hiding on the ship as well. The only thread that might lead to the answer is a phrase Mrs. Allain accidentally drops about paintings by the English artist John Constable…