For centuries the mysterious heart disease Hypertrophic Cardiomyopathy, abbreviated HCM, had claimed the lives of people without being known to science and with few, if any, cures available to patients. The first scientist to describe the physical manifestations of the disease was the Italian doctor Giovanni Lancisi in the year 1700.

More than three centuries later HCM had affected the lives of the US entrepreneur Louis and the Italian teacher Chiara in different ways and leads to their meeting in a Florentine hospital. Could they beat HCM? Find out in The Green Tunnel.