Last year I visited Elmina Castle, a slave fortress on the coast of Ghana. It’s a beautiful white-washed building, very similar in style to Cape Coast Castle, the slave fortress where Yaa Gyasi sets key pieces of action in Homegoing. The castles are two of about 40 such structures that were built along the Ghanaian coastline by Europeans. They were trading posts that became holding prisons for millions of West African slaves who were then shipped off to the Caribbean, the US and South America. The structures are huge. They dominate the coastline. Markets and towns would have grown up around them, like the town of Elmina that sprouted up around Elmina castle. It is impossible that the locals did not know what the primary trade from these castles was. Did it trouble them? Why was the trade in African bodies accepted? Gyasi takes us aside, sits us down, and says, ‘let me a paint you a picture, let me show you how the system worked.’