Detective Murdoch is on the case when police discover two bodies at a building construction site. Their initial estimate is that the bodies have been there for about 5 years but the remains are found in a peat bog and as a result are very well preserved. Both bodies, one man and one woman, are approximately 40 years old and Dr. Ogden's examination reveals that they were both poisoned with cyanide. Further evidence however shows that both bodies have been there for at least 22 years. But that's incorrect as well as further evidence then points to 1836 as the likely year of death. Murdoch manages to locate locate the now elderly daughter of the victims, Rebecca Hastings and her husband Charlie. He also realizes that either she or her husband killed her parents or possibly one of the three foster children who also lived there at the time, Alice Nugent, Horace Mooney or Michael Webster. Meanwhile, Constable Crabtree's cousin from Belleville, Ontario, Penny Ranton, comes to Toronto to attend secretarial college. It turns out she has other reasons for being there as well.