The year is 1979. "In Devon, an open briefcase is found on the seat of a commuter train and sensitive documents are scattered around the compartment. Further back down the line, the body of a man floats face-down in a river. Alex Swan and his associate Andrew Gable discover that the man was a biochemist working at the highly secret Microbiological Research Establishment. The dead man's trail leads Swan to what looks like a major government cover-up, codenamed Operation Butterfly."