The Second Book of Ore: Waybound

Phoebe Plumm and Micah Tanner are a long way from home and entrenched in a struggle with no end in sight. The Foundry, an all-powerful company that profits off the living metal creatures of Mehk, is unleashing a wave of devastating attacks to crush the rebel army of mehkans known as the Covenant and capture Phoebe and Micah, dead or alive. But the Covenant believes that their ancient god, Makina, has chosen Phoebe for a sacred task: to seek the Occulyth, a mysterious object they hope can turn the tide against the Foundry.
With her father gone, Phoebe's once unshakable determination is broken, and while Micah tries to uphold the vow he made to protect her no matter the cost, their enemies are closing in and time is running out.