Papillon by Henri Charrière (1969) — The memoir of a French convict sent to the penal colony at Saint-Laurent-du-Maroni and the Iles du Salut, and his repeated attempts to escape. Massively entertaining and largely responsible for the Devils Island mythology. Historians have questioned some of the details, but as a portrait of the penal colony system it remains vivid and absorbing. Essential reading before visiting the Iles du Salut.
The Dreyfus Affair by Ruth Harris (2010) — A thorough account of the most famous case to pass through the penal colony. Alfred Dreyfus, a Jewish French army officer, was falsely convicted of treason and spent years imprisoned on Devil's Island before his eventual exoneration. The affair tore France apart and helped define the modern concept of a miscarriage of justice.
Maroons and the Postcolonial State edited by Kenneth Bilby and others — For readers wanting to understand the Bushinengue (Maroon) peoples of the Maroni River, their history of resistance, and their complex relationship with the French state. Academic in tone but rewarding.