The daughter of a judge was killed as her father looked on while on the phone with the killer. The Five-O were called in to investigate and figured that someone the judge had convicted may have been out for revenge. The D.A. gave the Five-O a list of suspects that had sent threats to the judge, and they tracked down a suspect. However, at the same time the Five-O had apprehended him the D.A.'s son was murdered with a car bomb.
Further investigation led the Five-O to a former fellon, Travis Roan, whose son was sent to prison and murdered while incarcerated. He blamed the D.A. and the judge for his son's death, as well as his son's public defender. The Five-O managed to stop Roan before he could kill the public defender's son.
Danno's brother Matt arrived on the island for a visit. Matt was under investigation by the FBI and was going to be indicted. Danno didn't want to believe his brother was guilty, but Matt confessed that he had stolen money from his clients. Danno convinced his brother to turn himself in. Matt fled the country at the last minute instead, and Danno was unable to stop him.