In the 1830s, after the abolition of slavery, the British government needed to replace the former slaves who had worked in the colonies, so they devised a system known as “indentures labour”. Illiterate Indians were persuaded to put their thumbprints on contracts, with the promise of work abroad. Most had little idea what they were signing. More than a million were shipped out to distant corners of the Empire; few returned.

Writer David Dabydeen, whose great-grandfather was a labourer on the sugar plantations of British Guyana, tries to trace this part of his family history in an informative and well-made documentary about a little-known aspect of imperial history, told more in sorrow than in anger.