Sylheti orphans Ayan Miah and his elder brother Kazi are constantly reminded by their mission teachers of their low caste background and how their aim in life should be to become 'respectable'.

He finds work as a slave laborer aboard The Bengal, a British steamship making the journey from Calcutta to London.

Ayan is forced to rethink his situation after he realises the financial security that is promised to the lascar is far from the harsh reality of working in prison-like conditions of the trading ship.

In London, an encounter with the police turns into a blessing when Ayan and Akbar are taken to a hostel where Louisa, an Italian prostitute, teaches them English and shows them how to earn money as street musicians.

But Phoebe misses the privileged life she once had and her misgivings are accelerated when Jack the Ripper terrorises the neighbourhood and a brutal murder takes place close to their home.

Bradford Hillary wants Ayan out of his daughter's life once and for all and falsely accuses him of theft and blackmail, sending him to prison again.

After serving a five-year prison sentence, Ayan meets a ship painter Malik, a fellow East Indian, at the London Docks.

Ayan discovers that the boy's father was also a Lascar who had escaped The Bengal and became involved with a white woman whose family loathed the idea of their daughter being in love with a dark-skinned Muslim man.

Financially secure, Ayan decides it is time to return to Sylhet, East India to build a home, and care for his elder brother.

"[3] Amber Ali of Asian Image said of the book, "Meticulously researched, Lascar delves into the trajectory of one man's life which is reminiscent of a whole genre of men and their struggle for basic happiness, and the inability of individuals to surmount the social and psychological forces that determine their lives.