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.

1839年夏、嵐の吹き荒れる夜、キューバの海岸沖でスペインの奴隷船ラ・アミスタッド号の船倉に捕らわれていた53人のアフリカ人たちが暴動を起こした。乗務員を殺害し、船を乗っ取った彼らの目的はただひとつ、母国アフリカに帰ること。だが彼らは2ヶ月後、アメリカの沿岸警備船に取り押さえられ投獄。死刑確実となる。

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.

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