At the age of 38, police forensic expert Aleksandra Ladynina has never been married and has no plans to. She lives with her mother, a mathematician who spends all her time at conferences, leaving Aleksandra to bring up her 13-year-old fidgety little brother nicknamed Squash. The rest of the time, Aleksandra is married to her beloved career believing only in facts, which, unlike people, will never lie. She is valued, respected and feared by her colleagues. One day her entire "debugged" life in medical gloves is turned upside down when a new Head of the "Slaughter" Division is appointed to the Police Department where Aleksandra works. Ilya Vlasov is a practical joker and famed womaniser and had known Aleksandra from the time when they were at kindergarten together. He used to call her Susha. Up to this day, she thought that the romance they had 18 years ago was long forgotten. However, even Aleksandra may, from time to time, make a mistake.