Think of this pilot as "Hawaii Five-O Lite". It's set in Hawaii, it's an action/adventure crime drama, lots of scenes feature boats and palm trees and polyester fabrics and garish shirts...it even stars the character actor "Zulu" in a supporting role. Oh, there are some minor differences - Roy Thinnes is supposed to be some front-line undercover agent, and the supporting cast is much smaller (and less interesting), but basically the atmosphere is still the same. Problem is, "Hawaii Five-O" (another QM product) already existed at the time and had run for years. It filled the market demand for Hawaii-based crime dramas quite adequately. Code Name: Diamond Head may have been intended as the hier to H50 as the older series eventually dwindled away...but it comes across as a superfluous, 2nd rate copy. It doesn't suck, but it's completely derivative and doesn't do anything as well as the original.<br /><br />There is some decent acting talent involved here. Thinnes is an old pro, and he gives the role his best shot, and he isn't bad. But Thinnes is only as good as his material and his director. Ian McShane is in here as an evil spy master named "Tree", and McShane tends to be the most interesting actor in any scene he appears in. But he's phoning his part in here. Frances Ngyuen is reasonably exotic looking, but her astounding skinniness, opaque features, thick accent and wooden delivery aren't the stuff of which dreams are made. Relying on her to supply the 'romantic interest' for Thinnes was probably the series' biggest mistake. At least for for a series aimed at white audiences brought up with Marsha Brady and Peggy Lee as our love goddesses. Give her another 30 lbs and a year with a dialog/voice coach, and she might cut it. Zulu is, well, his usual self - enjoyable in bit parts, but he isn't a person who can carry a feature by himself. <br /><br />In addition, the plot and dialog are strictly by-the-numbers, with nothing to distinguish them from any other Quinn Martin production. And by this point, the American TV audience had seen a whoooole lot of QM productions....I think "CN: DH" was one too many, and it sank without a trace. It wasn't the really the actors' fault, and I hope they walked away from this with a decent paycheck and one more entry on their C.V.s. <br /><br />MST3000 revived this for their treatment in their sixth season, and they had a lot of good natured fun with it. Worth seeking out in that version if you enjoy the MST approach to movie japery and lampoon, but I can't imagine anyone caring about this pilot for any other reason.