Amistad begins with the event that made that ship's history different from other slave ships: the gradual extraction of a nail from the ship which allowed Cinque (also known as Sengbe) to free first him and then the other slaves on board. The first ten minutes are designed to evoke stark terror, as the freed slaves attack their Spanish captors, killing all but two of the ship's sailors, who they keep alive in order to sail back to Africa. In the beginning Tappan and Joadson are not eager to have Baldwin's assistance, but they accept his legal efforts in the end, and he proves persuasive enough to win the first two trials. Through the course of those two trials Baldwin's attitudes change toward Cinque and the Africans, and by the picture's end he has become a committed abolitionist (Watts 2007).
Baldwin finds documents that seem to prove the ship originated in Africa and not in Cuba, which would show that the Africans were not born on plantations (thus, legally considered Spanish slaves whose ship had strayed into American waters), but rather that they had been captured in Africa and were the fruits of the illegal international slave trade (Alexy 1993). The abolitionists sense that in this second trial, the deck has been stacked against them and they appeal to ex-President John Quincy Adams for assistance, but he turns them down. Isabella II writes numerous letters to the United States protesting that the slaves must be returned, and John C. Calhoun is threatening that civil war may be the outcome if the case is not resolved in a pro-slavery fashion (Adams & Welsch 2005).
However, through Cinque's testimony, Baldwin, the judge and others come to sense the horrors that the slaves have encountered, and despite his political ambitions, Coughlin the judge rules that the Amistad survivors should be given their freedom and returned to Africa, while the slavers should be jailed for murder. Apparently Cinque and the Africans will get their freedom, but the government (at the behest of Van Buren) appeals the case to the Supreme Court. After almost two hours in the film, Baldwin and Joadson are appealing to John Quincy Adams for help again, but this time he decides to assist them. Communicating through his interpreter, Cinque sends a series of legal questions about jurisdiction and international treaties to Baldwin and Adams, provoking Adams to angrily request that Cinque by brought to meet him (Alexy 1993).
Two sentences from the case's opinion are read by a justice (never identified as Joseph Story until the credits, and portrayed by Justice Blackmun) indicating that the Amistad survivors are to receive their freedom. After Cinque has his farewells with each of the film's principal characters (Adams, Joadson, Baldwin), he is next shown on a boat destined for Africa. The film closes by showing each of the main characters and subtitles indicate their fate (e.g., Van Buren is replaced by William Henry Harrison; Cinque returns ...