Sold into slavery to pay for his father's foolishly wasteful spending, Onesimus finds life as a slave especially hard. His memories of his own treatment of slaves compare badly to the treatment he receives at the hands of his Christian master, Philemon. But when he is falsely accused of theft and cannot prove his innocence,he can't believe his punishment will be any less than what he would have meted out in his own household. Filled with fear, he steals a purse of money and runs away, planning to leave Greece and lose himself in the crowded streets of Rome. On the way, he hears stories of Paul, who survived the bite of an adder but insists he is only a man, not a god.

When Onesimus finally meets Paul, he finds himself attracted not only to the man, but to the God he serves. After studying with Paul a while,Onesimus goes back to Philemon to "make his paths straight." Adventures and miracles along the way abound.Will Philemon accept him back or sell him? Will his fellow-slaves welcome him? What of the "girl he left behind?" Is there happiness in store for Onesimus or will sorrow be his lot?