 Now installed in London as a Professor at the university, Sam Ryan is called to assist when a helicopter carrying 16 men crashes in the North Sea en route to a drilling platform. The pilot s body is recovered and the autopsy reveals he suffered a heart attack between the time he sent a distress signal and the time the helicopter crash. He had recently postponed his annual medical check-up but Sam suspects there is more to this than meets the eye. In completing the autopsies on the recovered bodies, it seems that the aircraft may have suffered a catastrophic failure.