ATF Agent Kathy Millwood, played by Melina Kanakaredes, followed an arsonist from California to the islands in "Nanahu" (Episode 16, Season 5). She badly wanted to catch him because he torched her house and killed her husband while she was chasing him back in California. With Five-0's help, she was able to complete her journey and finally get a small piece of closure in her life.
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