En 1839, "l'Amistad", navire espagnol transportant des esclaves africains, est pris dans une violente tempête au large de Cuba. Une cinquantaine de prisonniers réussissent à se libérer de leurs chaînes et se retournent contre leurs bourreaux, qu'ils passent par les armes. Cinqué, leur leader, oblige le capitaine à les ramener vers l'Afrique, mais celui-ci, profitant de son ignorance, met le cap sur l'Amerique. Jetés en prison, les mutins vont être défendus par deux fervents abolitionnistes, Theodore Joadson et Lewis Tappan, qui engagent un jeune avocat, Roger Baldwin.
Amistad is the name of a slave ship traveling from Cuba to the U.S. in 1839. It is carrying a cargo of Africans who have been sold into slavery in Cuba, taken on board, and chained in the cargo hold of the ship. As the ship is crossing from Cuba to the U.S., Cinque, who was a tribal leader in Africa, leads a mutiny and takes over the ship. They continue to sail, hoping to find help when they land. Instead, when they reach the United States, they are imprisoned as runaway slaves. They don't speak a word of English, and it seems like they are doomed to die for killing their captors when an abolitionist lawyer decides to take their case, arguing that they were free citizens of another country and not slaves at all. The case finally gets to the Supreme Court, where John Quincy Adams makes an impassioned and eloquent plea for their release.