Defiant's crew is part of a fleet-wide movement to present a petition of grievances to the Admiralty. Violence must be no part of it. The continual sadism of Defiant's first officer makes this difficult, and when the captain is disabled, the chance for violence increases.

In 1839, the slave ship Amistad set sail from Cuba to America. During the long trip, Cinque leads the slaves in an unprecedented uprising. They are then held prisoner in Connecticut, and their release becomes the subject of heated debate. Freed slave Theodore Joadson wants Cinque and the others exonerated and recruits property lawyer Roger Baldwin to help his case. Eventually, John Quincy Adams also becomes an ally.

The MacIver brothers (Michael Redgrave, Griffith Jones) build the first ship to cross the Atlantic by steam power alone.

The struggle of a man to build a steam ship to take him across the Atlantic in spite of all setbacks, and his win against a crack sailing boat in the early 19th century.