A young man walks through the streets holding a sign that reads, “The trial for the Tobata Incident 19 years ago was a frame-up!” He has taken up the fight alone on behalf of his innocent father, who is serving time for murder.

Maki, a porter at the Sakura Hotel, finds a body in Room No. 2 and picks up a piece of paper on which is written "one-third of the key", also the part of a key. From a newspaper he learns that the dead man is an official who has been detained as a suspect in a bribery case involving 150,000,000 yen and that another suspect named Matsunaga is still in custody. Maki realizes that if he can obtain the other two-thirds of the key, he will be a multi-millionaire.

Jiro, a young yakuza, and Mami, a diplomat’s daughter, are two young lovers from different worlds. Having met by accident, they soon discover a new life together. But their love is ill-fated. Mami's family will not accept her choice, while leading an honest life seems like an unattainable goal for Jiro. Can there be anything else but a tragic ending?