A biological pathogen threatens all life on Hawaii.
I really like the idea of this episode and there's lots going on - in fact too much is going on and it gets away from the writers' abilities somewhat.
Alex is a scientist who has dropped out of the government's biological warfare program so that he can produce his own deadly strain of bacteria and show humankind the "folly of their ways". Enter Jonathan Kaye, hot on his trail and involving McGarrett and the Governor as usual. Lots of good tension between these guys in the normal "Five-O" fashion. And Ed Flanders (as Alex) does a very good job as does Loretta Swit as Wanda - it really is a bittersweet relationship they form. There's just a lot of unexplained things happening. Alex is vaguely sick throughout this episode and Part 2 and we never know why. When Wanda calls the private lab to check on Alex, Danny Williams somehow "senses" that she is a telephone operator for no rational reason. That would be OK, but the puzzling wild guess ends up being how "Five-O" tracks down the major break in the case. Alex also has a blind friend on the island who carves scrimshaw, its a nice character but how he even knows the mainland scientist is unclear.
There's the usual bad science, casually mixing up terms like "bacteria", "virus", and even "protoplasm", the "aerosol" nature of the infection is almost lost by Part 2. Still, its a timely episode - when it aired the US was finally pulling out of biological weapons research for good. And there is a sense of tragedy here that's accomplished. Part 2 is even weirder but almost as effective. Solid story, I think it would have been possible to edit it down to essentials without losing the message -but there are great elements I wouldn't lose.