Hill, a chaplain in the British navy in the 1830s and 40s, travelled from Rio de Janeiro to Mauritius, via Cape Town on board the Cleopatra in 1842. Hill's ship then cruised the southern Indian Ocean as part of the naval anti-slavery patrols. He describes stops in Madagascar, Quilimane and the port of Mozambique, where he observes: "I met in the streets a much greater proportion of shackled slaves than at Rio Janeiro" (8). He also recounts the capture of the Progresso with 447 slaves on board, and the horrors of the journey from Mozambique to the Cape on board the crowded ship, with a 40% mortality rate. He is critical of the naval patrols, concluding that conditions had only worsened since the slave trade had been officially abolished, that naval ships were unequipped to deal with the captured slaves, and that slavers were allowed to escape with impunity.

The testimonials printed in the second edition of Hill's book include a review from the New Monthly Magazine, which states that it will "do more good in the way of practical results, towards the suppression of the Slave Trade, than fifty meetings at Exeter Hall".