Lyon's account of a trans-saharan expedition in Northern Africa, which left from Tripoli in 1818, describes the caravans of the trans-saharan slave trade that he encountered during his travels, and gives an eye-witness narrative of the ill-treatment of slaves, who were often beaten or left behind if they could not walk at the pace of the caravan. He also gives a brief account of practices of slavery in the area, particularly in chapter seven, which describes the Fezzan region (now southern Libya) and the legal regulations of slave ownership there.

With maps of Lyon's route and coloured illustrations, including one entitled 'A Slave Kaffle'.