A black suitcase is abandoned at a garbage collection point. Lao Li, a homeless man who survives by scavenging for food, drags it to a park. But when he opens the suitcase, he is horrified and flees. As the police investigate the suitcase's origins, they hear from people nearby that Lao Li has been acting strangely and eventually bring him in for questioning. Lao Li admits that he dragged the suitcase away but insists that he did not hurt the person inside. What clues are hidden in the dark blue car parked near the garbage collection point?