This one plays kind of like a Bond film, even though it takes place in Hawaii, and the entire Five-O team figures in prominently.

Lord Danby (Dan O'Herlihy) is both an English Lord and an MI6 spy, who is apparently in Hawaii as a double agent, making a deal with the Chinese to sell British secrets. He's there with his much younger wife (Juliet Mills), who apparently has no idea of much at all, including the full details of their finances. Danby is said to have lost almost his entire fortune in bad business deals, thus motivating his sale of secrets to the Chinese.

Shifty-but-dignified MI6 agent Harry Wells, also an older man, is in Hawaii after him. Throughout the episode, Wells and McGarrett feign cooperation, but neither seems to trust the other, and Wells is clearly hiding many things from McGarrett, a few of which are briefly shown to the viewer. (For one, Wells has another agent working with him on the islands, who is told, "We can't be seen together anymore" near the beginning of the episode.)

Danby shoots a man following him (one of Wells' agents) near the beginning, then runs away. He then fakes his own drowning, and most of the episode involves both Wells and McGarrett trying to find him.

The plot has various twists, turns, and double-crosses, resulting in one agent dead, and another arrested for murder.

They did a good job cramming a lot of plot in the 49 minute runtime. It felt like a double-episode, and not in a bad way. I was actually quite into the story!

However, it was not a perfect episode, by any means. As noted by Mike in his review, the tailing of Danby was laughably bad, to the point where it was a distraction to the viewer. Even Danby himself seemed to be constantly noticing some kind of tail. Duke's tail of Wells near the beginning was also poorly executed, with Wells ultimately outsmarting him, and tipping his hat as he rode away on a double decker bus.

Wells carried an umbrella throughout the entire episode, despite no rain being shown in Hawaii at any point. (It rarely rains on Five-O, which must have been quite a challenge for shooting, given the frequency of rain in Hawaii!) The umbrella seemed to be more of a fashion statement, and McGarrett is shown angrily seizing it at the end, in the final seconds of the episode!

Danby's wife seems mostly loyal to him, but takes one strange action seemingly contradicting that. When Danby gave her a clumsily coded telephone message as to where to meet, she followed Wells' instructions and first informed him where Danby would be! However, when she met Danby right after, she tried to warn him, only to have Danby refuse to listen. Very strange scene. I still don't understand why she made that call to Wells. Was something cut from the episode which explains that?

CIA man Jonathan Kaye is seen "hassling" McGarrett over the telephone throughout the episode.

Overall, pretty enjoyable, and I give it 3.5 stars.