McGarrett meets his match in Dr. Grant Ormsbee, a grumpy and aggravating scientist who is sheltering a suspected Chinese defector.

Five bodies are found in the crater of Mauna Loa contaminated by radiation from illegal plutonium, and Five-O must find and confiscate this deadly toxin.

While searching for parts from a sunken Soviet submarine, McGarrett become suspicious about the particular parts that are being recovered.