Keahi and Kwon, emergency responders for the Hawaii Department of Water, Wind and Sun, bolt from a cookout at Bellows Beach Park to respond to an explosion and fire at a pet shop near Waikiki. Is the disaster related to an earlier explosion at a childcare facility playground? They race to the site to try to prevent further explosions and worry that their efforts may be thwarted by corrupt senior officials. While Keahi investigates the explosion, his nephew, Liko, returns to Hawaii and re-kindles his crush on Toi, a co-worker of his uncle Keahi and an immigrant from Vietnam. To Keahi's dismay Liko drops a bombshell: he intends to scuba dive the dangerous lava tubes at Shark's Cove just north of Waimea Bay. Keahi forbids it, and the person who was to accompany Liko on the dive proceeds with the dive without Liko and drowns.