The Hawaiian police try to catch a killer who decapitates victims. Danny and Christopher discover that their food poisoning case isn't as open and close as they first surmised.
Gains tries to stop a bank robbery by going undercover and joining the crew. Harrison and Declan try to nab a mob boss at a family gathering.
A serial killer returns to their old mode after a six year absence forcing Harrison and Declan to open the long dormant, unsolved file. Declan has a bad go at things after offending a Hawaiian god. Gains and Edwards try to stop a series of carjackings.
Harrison and Declan have a ticking clock working against them when a judge is murdered and they have only three days to nab and secure their lead suspect. Gains and Edwards try to take down a group of heroin dealers.
Declan tries to bust a sex-slave ring after a teen is kidnapped.
Gains and Edwards discover an island that produces crops of marijuana but claims to be an independent nation, causing political ramifications.
A murder is committed over the death of an island queen that happened centuries ago causing a rift in the island's populace. Harrison and Declan try to help an informant make their court date.