Metal Sky. The Jack Stein Novels, #2

Two years after Wyrmhole, Jack Stein and his young ward Billie have settled into a quieter life in Yorkstone - until a simple missing-persons case turns up a body, a corpse, and a strange artefact that everyone seems desperate to possess. As rival buyers close in, Jack finds himself facing Christian Landerman: a man convinced that humanity's future belongs to whoever is ruthless enough to seize it.
Jack has to decide how far he'll go to keep it out of the wrong hands - and what he's willing to risk to protect the only family he has left.