In the early sixteenth century, a young English sugar trader spent a night at what is now the port of Agadir in Morocco, watching from the tenuous safety of the Portuguese fort as the local tribesmen attacked the 'Moors'. Having recently departed the familiar environs of London and the Essex marshes, this was to be the first of several encounters Roger Barlow was to have with unfamiliar worlds.

Barlow's family were linked to networks where the exchange of goods and ideas merged, and his contacts in Seville brought him into contact with the navigator, Sebastian Cabot. Merchants and Explorers follows Barlow and Cabot across the Atlantic to South America and back to Spain and Reformation England. Heather Dalton uses their lives as an effective narrative thread to explore the entangled Atlantic world during the first half of the sixteenth century. In doing so, she makes a critical contribution to the fields of both Atlantic and global history. Although it is generally accepted that the English were not significantly attracted to the Americas until the second half of the sixteenth century, Dalton demonstrates that Barlow, Cabot, and their cohorts had a knowledge of the world and its opportunities that was extraordinary for this period. She reveals how shared knowledge as well as the accumulation of capital in international trading networks prior to 1560 influenced emerging ideas of trade, 'discovery', settlement, and race in Britain. In doing so, Dalton not only provides a substantial new body of facts about trade and exploration, she explores the changing character of English commerce and society in the first half of the sixteenth century.