Professor Ian Hood is a former physics professor recruited by the British government as its on-call scientist/detective and Jensen's Young is the companion bodyguard hired to protect Hood from the people who want to see his work put to an end.
After a child's kidney tumor disappears, his father credits the cure to water from a particular spring. Hood and Rachel rush to the scene to investigate - along with a horde of hopeful cancer patients. But if the water has such curative power, why does it seem to make so many people sicker?