Lukas and Conny are in a streetcar and on their way to a casting at a photography studio – they are already very excited. While Lukas concentrates on looking over the model agency's casting material, Conny observes two youths badgering other passengers in the streetcar. Finally, one of the passengers intervenes and tries to reason with the youths. But that only gets them even more agitated. When the man gets off the streetcar, the rowdies jump off too and follow him. Conny points out to Lukas that the man is in impending danger, and runs after the youths. Lukas takes a moment to think things over, and then it's too late – the streetcar doors close right in front of his nose.
Lukas really gets worried when he waits in vain at the casting for his friend and can't reach him by telephone. Someone finally answers the telephone. But it's Inspector Meininger, who informs Lukas that Conny is in the hospital and is severely injured. And the man Conny was trying to help is also injured. Meiniger is outraged that none of the numerous streetcar passengers intervened. And there is no trace of the thugs. Could Lukas have prevented this attack? Now he wants to find the perpetrators at all costs, and in doing so he puts himself in serious danger.