Time of the prima donnas

Ema Šubrtová works as a teacher at a grammar school, occasionally guides tourists around Brno and enjoys a carefree time with a group of friends without commitments. When her friend Leona is murdered, despite the protests of her brother Jirka, the police officer investigating the case, she begins to search for the killer on her own. Her friends are also suspected of the murder, especially the son of Vlasta Potocka, a wealthy Brno patroness.
Ema discovers that Leona's death may be linked to an unsolved jewellery and expensive watch robbery three years ago. She meets the charismatic Martin, but refuses to trust him because he has not been honest with her from the beginning and their meeting was no coincidence. His sister Filipa is also a renowned gemstone expert. Are they the perpetrators of this robbery? And what role does an old Spartak watch play in the case?