Hantaviruses cause severe and sometimes fatal respiratory infections, but how they infect lung cells has been a mystery. Researchers report that hantaviruses gain entry to lung cells by ‘unlocking’ a cell-surface receptor called protocadherin-1 (PCDH1). Deleting this receptor made lab animals highly resistant to infection. The findings show that targeting PCDH1 could be a useful strategy against deadly hantavirus pulmonary syndrome.