A gang of criminals devise a scheme to defraud insurance companies by faking heart attacks. Their plot includes a method of altering electrocardiograms. The setting is 1931 when electrocardiography was a relatively new diagnostic tool.

Stuart Downing, a young physician, suspects the scheme, but digging out the evidence proves a deadly pursuit. Downing is up against a a devious lawyer, unscrupulous doctors, crooked insurance agents, and killers.

Downing must match his ingenuity against that of the scammers with an unimaginable threat lurking at his every move.