A light plane crashes near a beach and a few days later, two elderly sisters are killed in their sewing supply shop.  Both crime scenes show evidence of explosive weaponry.  Wallander makes a strange discovery about one suspect, which leads him back to a traumatic experience years prior.

Falk, the man found dead in Firewall Part 1, was a brilliant, mild-mannered computer programmer who kept to himself. Wallander and colleagues rush to find the connection between him and the blood-stained taxi in Part 1.

A taxi is found abandoned, smashed up and full of blood. Two young girls confess to the murder, but refuse to say where the body is. The next day a man named Falk is found dead at an ATM, receipt in hand.  Wallander strains to find a connection between the two cases.