The first several pages contain an account of the author's life:
William Wells Brown, the subject of this narrative, was born a slave in Lexington, Kentucky, not far from the residence of the late Hon Henry Clay. His mother was a slave of Dr. John Young and his father was a slaveholder. After the doctor moved to Missouri his slaves were under the control of an overseer named Cook. When William was 12, the doctor moved to St. Louis; William was sent to work for an innkeeper named Freeland. After running away, he was captured and returned to the "monster" Freeland. William was later lent to Elijah P. Lovejoy, an editor of an abolition newspaper who was later murdered at Alton, Illinois, by a gang of slaveholders from Missouri.
William W. Brown then worked on a steamer until he was hired by slave trader James Walker. "Here subject of our memoir was made superintendent the gangs of slaves that were taken to the Orleans market. In this capacity William had opportunities far greater than most slaves of knowledge of the different phases of the institution."
Eventually William was sold to Captain Enoch Price, owner of the steamboat St. Louis. He managed to escape again and was helped by a Quaker named Wells Brown; that's how William became William Wells Brown. William Wells Brown continued on his way to Canada.
William Wells Brown then went to Monroe, Michigan, where he opened a barber shop. After a few more twists and turns in his life, he became a lecturer. His wife died in Buffalo, New York, in 1851.
Mr. Brown remarried in 1860; there's a reference to his wife, Anna Elizabeth (Gray) Brown "who later published Brown's work under the imprint A.G. Brown."
A summary of Clotel can be found here.