Here's an episode with guerrillas trying to steal arms from Hawaii and sneak them back to their country. If I recall, this is the first episode like this but it will not be the last.
The band is led by Elpidio Acuna (Henry Silva) who is trying to fight against his oppressive government. During the warehouse standoff and after the guns are stolen, McGarrett breaks in through a skylight and wounds Acuna who fights this injury for the rest of the episode. In the end, Five-O tracks down Acuna and the arms. They take him in alive much to the relief of his pregnant wife Marla (Julie Gregg).
Check out Mr. Mike's awesome review of this episode: http://www.fiveohomepage.com/5-0log2.htm#28
I mention the review because there is one point I will definitely agree on, the music. It's "cheerful" and "perky," not what you would expect for so serious a subject matter. Another point I agree on, the scene in McGarrett's office where Danno and Chin make snide comments about Kono's weight. Were they trying to be funny? Because it just comes across as mean, not what I would expect from these guys - that's a bit disappointing.
This episode also gives us some stock shots such as the HPD unit driving by the church. I think the ambulance driving down the street at night at the end is another stock shot but it was used before.
I don't know if a change of music would have helped this episode that much but it would have helped. I agree with Mr. Mike and his 2.5 star rating. Happy 50th!