The Day of Atonement by David Liss

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Sebastião Raposa is only thirteen when his parents are unjustly imprisoned, never to be seen again, and he is forced to flee Portugal lest he too fall victim to the Inquisition. But ten years in exile only serve to whet his appetite for vengeance. Returning at last to Lisbon, in the guise of English businessman Sebastian Foxx, he is no longer a frightened boy but a dangerous man tormented by violent impulses. Haunted by the specter of all he has lost-including his exquisite first love-Foxx is determined to right old wrongs by punishing an unforgivable enemy with unrelenting fury.

Source: Jewish Book Council