Dani and Caitlin, two 12-year-old Ottawa girls, have a talent for meeting ghosts. Fresh from their adventures with the spirit of fabled Canadian painter Tom Thomson, the girls find themselves in Quebec, across the river from the capital city of Canada, touring the Kingsmere estate of longdead prime minister William Lyon Mackenzie King. While there the friends run into someone famous for seeing ghosts himself -- the old prime minister, or at least his phantom!

King, affectionately known as Rex, presents the sleuthing duo with a series of problems. It seems developers are keen on despoiling the dead prime minister's estate, not to mention another city park dear to Caitlin's heart. Thrown into the mix are a couple of murders, a former prime minister's place in history, and maybe even a federal crime. Dani and Caitlin are on the job, and the politicians on Parliament Hill better watch out!