The third book in The Circle Opens series.
Daja and Frostpine are staying with some friends of Frostpine's. While they are staying there, Daja realized that the two eldest daughters of the family (the twins Niamara (Nia) and Jorality (Jory) possess ambient magic. She devises a testing mirror to determine the aspect of their magics. Nia is discovered to possess Carpentry magic and Jory to possess Cooking.
Since Daja has no skill in either of those areas, she entrusts the twins to local mages. Her only responsibility is in teaching them to meditate. Since the twins are complete opposites in personality, this proves to be a challenging task.
Meanwhile, Daja makes friends with a local firefighter, Ben Ladradun. He is trying to form an organized fire brigade from the villagers, but it isn't working.
Daja and Ben suspect that many if not all of the recent fires were set on purpose. As Ben searches to discover the 'ire-bug', Daja works tirelessly to make Ben a pair of living metal gloves to protect him from burning.