At first glance, the death of a teenage surfer in a small Maui town looks like a routine drowning.  A closer inspection by police captain Walter Alaka'i, however, reveals hints of a far more sinister cause of death.  Wanting an expert opinion, Walter calls in his niece, Kali Māhoe, who is both a detective and an anthropologist specializing in Hawaiian culture and tradition.  Kali is also alarmed by what she finds on the corpse, especially considering the spate of noperra-bō sightings that have been reported.  She doesn't really believe that a mythological malevolent spirit is wreaking havoc on her community, but there's no doubt that someone is up to no good.  Who killed the young wave rider?  Kali is determined to find out.

As strange things continue to occur in Hana, followed by another body washed ashore, the pressure mounts.  Can Kali figure out what is going on in her town before she becomes the next victim?