The hepatitis C virus is a prolific replicator, able to produce up to a trillion particles per day in an infected person by hijacking liver cells in which to build up its viral replication machinery. Now new research — in which scientists have for the first time used fluorescent proteins to image hepatitis C virus replication in live cells — shows that the microscopic viral factories are a diverse mix of big, immobile structures and tiny replication complexes that zip zanily around inside the cell.