When Willi strikes, no tissue stays dry. One could almost feel sorry for him—nobody likes him, nobody finds him pleasant, and everyone wants to get rid of him as quickly as possible. But he is truly no pleasant companion, bringing along a runny, dripping, or even blocked nose, watery eyes, and in the worst case, headaches. We present: Willi, the cold virus. Yet, even though almost everyone knows him, few are aware of the kind of havoc he wreaks in our bodies and the impressive means by which we expel him. Following her highly successful picture book debut "Gerda Gelse. General Wisdoms about Mosquitoes," the Viennese author Heidi Trpak presents another brilliant non-fiction picture book, in which she examines a phenomenon that couldn't be more ordinary.