Twin sisters Mattie and Tillie Holiday and their mishmash of rebel agents have been through hell and back, but they're still fighting. Reeling from the loss of two of their own, the group gathers to mourn, more determined than ever that the organization will fall at last.

But the organization is hitting them with obscure spell after obscure spell, and agents are falling or defecting left and right. It's becoming increasingly clear that the organization has gathered some pretty heavy magics over the centuries it's been around – magics that aren't available to most other mages.

Everything is hitting the fan all at once. Will their tiny army be able to muster enough force to take down the Pontiff and his goons once and for all? Or will they be squashed, like everyone else who has tried to take down the organization?

Brick by Brick is the fourth installment of the fast-paced Mathilda Holiday urban fantasy series.