In the epistle to Philemon, St. Paul says, in effect, "Dear Philemon: I have your runaway slave, Onesimus, who is returning to you with these letters, would you please free him and send him back to me, for he is very useful to me."
In the 1930s, John Knox began to suspect that the letters to Philemon and Colossians were related, and that the Onesimus named in both was also the Onesimus named as bishop of Ephesus in the letter of Ignatius to the Ephesians.
The runaway slave would then have been a young man in the second quarter of the first century, and a bishop at the end of the century.
It is conjectured that Onesimus collected the letters of Paul and published them as a group.
This book is an imagined biography of Onesimus.