New York–raised Hawaiian siblings Pili and Ioane "E" temporarily relocate from New York to Oahu with their mother Leilani to help her father, Kimo, whose health and financial issues are becoming serious. Pili is an avid geocaching fan, and her malaise at being separated from her beloved New York is assuaged by secretly liberating an old diary from her grandfather's art studio. Meanwhile, E is distracted from his own search for better Internet signal by the requisite pretty local girl, Hana, who has big dreams of her own. The siblings find themselves learning about their Hawaiian heritage as Pili goes on a Goonies-style quest for lost pirate treasure. Pili is aided on her quest by local boy Casper, a nerdy but resourceful boy with a big heart, and joined by E and Hana.