It was supposed to look like a heart attack, but the pharmacist Andreas Hölzenbein was murdered. In the botanical garden, he got into a fight with a stranger who gave him a life-threatening injection with a syringe. The bright, young witness Mia (Lena Meyer) claims to have observed all of this. But Commissioner Thiel is initially skeptical: doesn't the ten-year-old student simply have too much imagination? Very specificMeanwhile, Prof. Boerne is worried about his own state of health. In self-diagnosis, he had to realize that a tissue sample from his liver was probably unavoidable. That's why he immediately checked himself into the sanus clinic. So it's a good thing that he can conduct investigations into the Andreas Hölzenbein case from his sick bed. Even if the clinic staff doesn't like it at all...