There are 2 books in the Children of the Furnace series. The newest book is Crosstrees which came out in 2019.

1
Children of the Furnace

Book cover of Children of the Furnace
Truth died in the fires. Only through courage can it be born again. Under the iron rule of the Revelayshun, one boy discovers the truth… ‘Ty promised my ma he’d bring me up right. Bring him up to hear the rhythm beat, she said, and to feel the heartsblood warm.…
When you buy books, we may earn a commission that helps keep our lights on (or join the rebellion as a member).

2
Crosstrees

Book cover of Crosstrees
THREE HEROES WILL RISE

‘What we won was a small battle,' says Jace. ‘They'll be coming, fore we can turn this into a war.'

Wil and Leah saved Jace from the Revout's Fires, but retribution is swift and brutal.
The Revelayshun's soldiers are riding to hunt down the sister Wil…