Junior's semi-dodgy friend Hilo comes clean having helped a junkie sell to a scary teen girl a .38 caliber revolver, which McGarrett and the rest of the Five-0 members find to be a "community gun", used in over 47 cases including multiple homicides, so it's about impossible to work out who commit which with it. The gun was last used to murder the beached-up stepfather of buyer Bonnie, Owen Pearsen. The gun was surprisingly somehow connected to multiple Five-0 members: used to kill Duke's former partner, in a cold case of Steve's cop dad John, a deadly shop-robbery Danny walked into the day he moved to Oahu, and was used by Tani's ex-boyfriend who was a gang banger and let her softy 'kid' brother play macho with it.
—KGF Vissers