McGarrett and Five-0 help save an injured police dog and in turn use him to find who killed his partner and ambushed his team making a drug bust. McGarrett receives a visit by a former SEAL, who asks McGarrett for a job on the task force.
The lives of Five-0's informants are in danger when the HPD system is hacked and one ends up dead, forcing McGarrett to enlist the help of hacker Aaron Wright (Joey Lawrence), who he just imprisoned. Joey Lawrence Returns as Aaron Wright.
McGarrett and Adam join Junior at a bank heist in progress, forcing all of them to make difficult decisions in how to proceed into the bank and after the suspects. Tani has issues with a family member and gets advice from Lou.
Five 0 investigate the murder of the headmaster of a private school sending Tani and Junior undercover as prospective parents. Meanwhile Adam is forced to produce a huge amount of hidden money to save his life.
A flashback about the case that changed Danny's life and an answer about who shot him by meeting a woman who was married to the shooter. Jimmy Buffett returns, Alex O'Loughlin directs his first episode and plays the guitar.
A hitman, Leroy Davis (Frankie Faison), McGarrett's father failed to arrest comes to McGarrett to finally confess his crimes and admit where he buried his victims. Also, Jessie makes a dangerous decision that could ruin Adam's life.
Steve joins Junior and his SEAL team on a mission to capture an elusive person who is holding his mentor hostage; Gerard and Kamekona help Lou and Tani on a murder case involving art stolen by Nazis in World War 2. (#192)