I've never watched Hawaii Five-0 but, as near as I can tell from the preview they showed during football, the following happens in the next episode:

The cop main character goes to North Korea to do... something but get betrayed by Alex Mack and is kidnapped by the host of Iron Chef: America. The rest of his friends, who I assume are all police officers as well except for maybe Locke, then stage a rescue operation in North Korea (I guess cops in Hawaii make a lot of money and can all take vacation at the same time?). They are helped by Jimmy Buffett in a helicopter. Buffett may be playing himself, I'm not sure.

What an odd show.