Samuel L Jackson is joined by journalists Afua Hirsch and Simcha Jacobovici, along with Diving with a Purpose (DWP) – a team of underwater investigators dedicated to restoring their ancestors' lost history. Together, they investigate the events that ended the slave trade and the heritage and identity that was taken from the descendants of the millions of trafficked Africans. Outrage in Britain at the treatment of captured Africans gained momentum, and by the early 1800s, attitudes had changed. What was once a seemingly unstoppable trade was abolished in 1807. Samuel L Jackson and Afua Hirsh examine the petitions, books, prints and the work of activists that led to the end of 400 years of the slave trade, while the DWP divers explore the tragic history and wreck site of The London, a slave ship carrying slaves who had won their freedom and been re-enslaved. Having discovered that he is descended from the Benga people, Samuel L Jackson travels to Gabon and is welcomed into the tribe by the king and the elders, who share their traditions and stories. The DWP continue their work to recover the history of the enslaved and piece together this lost heritage. They travel to a community in Costa Rica to help a team of young divers look for evidence to support the stories that their African ancestors escaped from two Danish slave ships.