In the midst of World War II, Rick Blaine, an American expatriate, runs an upscale nightclub and gambling den in Casablanca, Morocco. The city has become a hub for refugees desperate to obtain exit visas to escape to America. Although Rick professes to be neutral and uninvolved in the war, his café serves as a melting pot for a motley crew of patrons, including Nazi officials, Vichy French, resistance fighters, and those looking to flee the devastation in Europe. The cynical and brooding Rick encounters a past lover, Ilsa Lund, who walks into his establishment with her Czech resistance leader husband, Victor Laszlo. The surprise encounter reawakens old feelings and plunges Rick into a tumult of emotions.

Ilsa's arrival coincides with the possession of two “letters of transit” that have come into Rick's hands—documents that are paramount for anyone seeking freedom from the war-torn continent. As Rick and Ilsa confront their unresolved past and the deep love they still hold for one another, her husband Laszlo is actively pursued by the local authorities under German influence, who seek to prevent him from continuing his fight against the Nazis. With the pressure to choose between his love for Ilsa, his own self-interest, and the higher cause of aiding the resistance movement, Rick must navigate a complex web of moral and emotional challenges.