The bodies of two serial killers are found with chess pieces in their mouths, so the team hunt for the vigilante.
A rogue MI-6 agent is the key to finding a terrorist who plans to cause the meltdown of nuclear reactors across Europe. McGarrett and Danny need the help of an FBI profiler to find a killer.
McGarrett's mother is captured and may face execution for trying to free Wo Fat's father. Chin is unable to delay Sara's adoption.
Chin gets kidnapped and ends up in serious danger of being executed. The team must find and rescue him before it's too late.
When a woman is found murdered in her home, Five-0 discovers a strong link between the victim and one of their own.