What if a man-made virus with the power to melt all plastic became as infectious as the common cold? When a plane crashes in South America, in quite extraordinary circumstances, it's up to Dr Quist's team to avert further disaster.

When John Ridge's father, Wilfred, becomes seriously ill, he decides to devote all his time to looking after him. Wilfred is then taken to hospital and put into the care of Doctor Cordell, but shortly afterwards he dies. Ridge is suspicious, and his investigations uncover a disturbing fact: Doctor Cordell is an advocate of euthanasia.