Danny steps out of his house and sees a fire from a large explosion in the distance. Max and Jerry are packing up Max's office. The body of a police sergeant from Milwaukee, visiting for a police convention, is found in the rubble of the explosion. McGarrett finds fresh tracks in the basement of the building. A heist crew accidentally set off the explosion by hitting a gas main. Gerard Hirsch helps McGarrett and Kono find G-Stealth, a freelance videographer who had shot the explosion site. Hirsch. G-Stealth tries to run but Hirsch accidentally captures him. G-Stealth's tape leads them to career criminal Jimmy Rorke, but instead they find a dead man, a former law clerk. The dead clerk's phone leads them to attorney Brian Hadley, who the dead man had contacted earlier that day. They piece together that the what was taken from the explosion site is being used to blackmail Edward Gabler, whose girlfriend, Heather Mayfield, had been stabbed with a knife years before, just like the dead cop. The thieves had stolen the knife from Hadley's vault. then blackmailed Gabler. Hadley rolls on Gabler. Evidence points to Heather's brother Alan being behind the robbery, murder and blackmail. Gabler and Rorke exchange money for the knife, but Alan interferes, pointing a gun at Gabler. Chin shoots Rorke, who had pulled a gun. McGarrett and Danny stop Alan from killing Gabler. Finally, there's a farewell party for Max, who gives a heartfelt speech.