When McGarrett gets a tip that someone is plotting a terrorist attack on Oahu, Five-0 searches for those behind it before it’s too late. Also, Chin and Abby have a very difficult decision to make.

Danny protects a coma patient showing signs of waking who was the key witness from his last HPD case before he met Steve and joined Five-0.

While working the murder case of one of the last survivors of the USS Arizona, McGarrett learns about his grandfather's important role at Pearl Harbor. Also, Adam uncovers bone fragments at his new construction job and asks Jerry to help him discreetly investigate.

McGarrett and Five-0 once again become entangled in the twisted mind games of serial killer Dr. Madison Gray when she stumbles into HPD covered in blood that matches Alicia Brown's, and claims amnesia.

While McGarrett and Danno celebrate Valentine's Day with their girlfriends, the rest of Five-0 investigates the murder of a man taking a class on how to land women.

When working a murder case involving the illegal practice of shark finning, Five-0 uncovers the possibility that a former Nazi war criminal may be hiding out in an old leper colony in Hawaii.

Five-0 must go up against an aggressive U.S. marshall, Lincoln, when a man wanted for murder escapes capture and seeks asylum in the sovereign land belonging to the Nation of Hawaii.

As Max prepares to say goodbye to his Five-0 ohana, they must investigate a murder during a police convention on the Island.

The team handles the fallout in Mexico after Chins problems, back on the Island Grover goes undercover and things get hot.

Five-0 races to Mexico where Chin puts his life on the line after his niece Sara is kidnapped.