A student in the Reading Room of the London Library, Marion Summers, suddenly goes into a seizure, then slips into a coma and then dies. But what first appears to be a simple tragedy, is soon revealed to be much more sinister. During the autopsy, it's determined that she actually died of acute arsenic poisoning. Brought to the attention of the Serious Crime Unit of Scotland Yard, the newly promoted Detective Inspector Kathy Kolla, with the help of...