On duty, firefighter Stefan Melfert is shocked to be sent to the apartment block he inherited, but rents to tenant families, living elsewhere while they spend every dime on renovations, and badly under-insured. Next morning, former tenant Iris Zielke is found burnt in the rubble, fiance Jürgen Polder claims to ignores why she returned there, but neighbor Peter Rilling heard them row that night. It could be a strike from the apparent pyromaniac who made no victims at several other places recently. 'Rent nomad' Werner Schöbel, who plays procedural games until he's evicted for paying no rent while filing complaints, threatened Melfert after his expedient removal and lived near most arson sites, he even smokes the type of cigar used as slow fuse.