American Mark Thackeray (Sidney Poitier) recently received his degree in engineering, but cannot find work. To make ends meet, he takes a job as a teacher in a rough London East End school populated mostly with troublemakers who were rejected from other schools for their behavior. While the students at first see Thackeray as just another teacher open for ridicule and bullying, his calm demeanor and desire to see them succeed gradually earn him their respect.