With the world changing war between Valnesse and the Sharawal alliance finally ending in a shaky peace, the neutral society of scholars known as The Silver Company is free to once more engage in its insatiable hunger for discovery, preservation, and study of old world knowledge.

Salyah Jerephey, a neophyte physician of the medical branch has reached the end of her studies and is nearly ready to be initiated as a fully-fledged member of the company. By order of the board of Superiori, her final exam is to be completed in the field, in the form of a mission.

That mission leads her into a place called The wall of Thesia - a ruin of the old world which now serves as a prison for the worst Equanor has to offer, mainly consisting of criminals who fought in the war. Salyah's well founded paranoia of that place has her questioning the reason for this mission, especially since it is her own father, the head of the medical branch and a member of the Superiori high table, who gave it to her.

From the mission briefing and the medical documents she receives Salyah learns about a mysterious illness that is ravaging Thesia - mainly the imprisoned population. Her mission is to identify which illness it is, draw blood samples from the patients, and bring them to the company.

Once she arrives, however, she quickly discovers that this illness is far worse than anything either she or her company imagined. It is nothing the world has seen before and has the potential to bring more deaths than the war ever did.

With her companions, she is forced to fight through the horde of crazed patients, but luckily she receives unexpected help from someone in Thesia - an enigmatic prisoner, a murderer of his own child, and an apparent friend of her family.