The lorry driver Misho and his mate Lazo kick down a girl riding a bicycle in the street. She is a laboratory assistant called Katerina. The trade union committee at the garage where Misho works is chaired by Raina, a childhood friend of his. She warns him that because of his persistent failure to fulfill the plan, he will be dismissed for his next offence. Misho calls on Katerina at the institute where she works and begs her not to report the accident. He is in love with her, but considers himself unworthy of a laboratory assistant's affection. Misho starts working conscientiously and becomes a model worker. Katerina's institute is to receive some new equipment, but there is no available transport. She asks Misho to help. This give him a chance to make a date with her which is followed by many others. While in restaurant, some colleagues of the girl poke fun at the driver: he kicks up a row and leaves without her. He confides his anguish to Raina. Secretly in love with Misho, she makes things up between him and Katerina. In his excitement Misho accidentally damages his lorry and is sacked. He is ashamed to admit this to Katerina and does not go to their next date. She thinks that he is having an affair with Raina and drops him. Misho's fellow workers intercede on his behalf and he is returned to his former job. His friends convince Katerina that she is in the wrong and after the final misunderstanding everything is clarified. The couple's kiss of reconciliation causes a traffic jam.