Doctor Quist and Doomwatch become embroiled in an inquiry into the heart-transplanting practices of Doctor Patrick. Several uncomfortable questions are raised: what has he been doing to a newborn baby that has been placed in his care, and should genetic engineering be permitted in society?

A vicar collapses during a sermon, and there are seemingly unrelated events, one involving John Ridge. The answers are out there, but are obscured by big business and profit margins.