The Singing Revolution by Clare Thomson (1992) — an account of the Baltic independence movements of the late 1980s, when Estonia, Latvia, and Lithuania used mass song as a form of peaceful protest. Thomson was there for the events and writes with an eye for the human detail. Essential background for understanding what the independence that Latvians still celebrate with fierce pride actually cost.
The Latvian Chronicles: Indriķis' Chronicle (translated by James A. Brundage) — the primary source for the founding of Riga in the early 13th century, written by a contemporary cleric who accompanied the crusading Bishop Albert. Not easy reading, but the chapters on the conquest of the Baltic peoples are extraordinary documents of how the city and country came into existence — and at whose expense.
Kolka by Nora Ikstena (translated by Margita Gailitis) — a novella by Latvia's finest contemporary writer, set in the village of Kolka on the Courland coast. Ikstena's prose is precise and unsentimental. Reading it before or after a trip to rural Latvia reframes everything you see.
Soviet Milk by Nora Ikstena (translated by Margita Gailitis) — Ikstena's most celebrated novel, telling the story of a mother and daughter across three decades of Soviet occupation. Riga is the backdrop throughout. It won the Latvian Literature Prize and has been translated into over twenty languages; it is the best single book for understanding what the Soviet period meant to ordinary Latvians.
Between Giants: The Battle for the Baltics in World War II by Prit Buttar (2013) — a military historian's account of the savage fighting that swept through Latvia, Lithuania, and Estonia between 1941 and 1944. Riga changed hands twice; the civilian population suffered catastrophically. Buttar is clear-eyed and draws on German, Soviet, and Baltic sources. Important reading for anyone who wants to understand why the war memorials in Latvia look the way they do.