S1, E1: Dr. Niklas Ahrend's first day at the Johannes-Thal-Klinikum takes an unexpected turn. As his sister Kathrin drops him off, he finds his mentor and friend Dr. Harald Loosen collapsed outside the entrance. Loosen has suffered a heart attack, and Niklas rushes to help. What was meant to be a fresh start quickly becomes a medical emergency and a personal crisis for Niklas.