Kai goes under cover with one of Hawaii's oldest surf gangs when a petty officer is murdered.
A violent convict escapes from an island prison in search of his stolen money and McGarrett's estranged sister arrives from the mainland.
When a college professor is killed, Five-0 goes back to school with Danny, who is posing as the professor's replacement.
A hospital emergency room shootout investigation puts the CSI team in the middle of a murder case involving the leader of a prominent street gang.
Magnum and Higgins are each hired by a different spouse who are in the middle of a contentious divorce to dig up dirt on the other. Rick and TC look into the death of an unidentified man and must share the news with his estranged daughter.