A coronavirus is threatening human health. SARS-CoV-2 is highly infectious and can cause severe pneumonia (COVID-19). A team has now found a promising approach to understanding the virus. Using the high-intensity X-ray light from the Berlin synchrotron source BESSY II, they have decoded the 3D architecture of the main protease of SARS-CoV-2. This protein plays a central role in the reproduction of the virus.