1664: Alouette Voland is the daughter of a master dyer at Paris' famed Gobelins Tapestry Works. With a gift for her craft and a drive to prove she is as good as the male dyers controlling the industry, Alouette dreams of creating her own masterpiece. But her boldness will put everyone she loves at risk.

1939: Kristof Larson is starting his medical residency in the same Parisian neighbourhood once dominated by the tapestry works. The shadows of his past have left him determined to improve conditions for the patients of the infamous Salpetrière asylum. But as war breaks out across Europe and Nazi forces descend on Paris, he could lose his career – and his life.

Alouette and Kristof are both ambitious, idealistic and brave. But faced with authorities who will do anything to silence them, the secret web of tunnels lying beneath the shimmering streets of Paris might be their only hope of survival.