the story: The Doctor inadvertently becomes tied into a weapon's AI.
what it's all about: If you really must retread familiar territory (and this is as familiar territory as can be found in the franchise, stop me if you've heard this one: the remnant of a long-ago war doesn't want to acknowledge the war is over), this is probably the way to do it.
"Warhead" is one of the many, many episodes in the series to handle artificial intelligence. Normally, it was with other forms of holograms, but like Next Generation and Data, the allure of the concept remained potent regardless, thanks to the Doctor. And the Doctor has one of his most unique experiences because of it: becoming the enemy!
Thankfully it's not like "Warlord," the Kes spotlight where that was quite literal, for one episode, but rather because (and not in the curious "Darkling" experience) his programming is overrun.
The ending becomes poignant, once the eponymous warhead has detached itself from the Doctor, when it chooses to sacrifice itself rather than further endanger Voyager. Actually, putting it like that makes the episode sound a lot like "Drone" at the start of the season. Second episode of the season and second-to-last episode...I don't think that was particularly coincidental.
- franchise - A familiar plot revisited.
series- Becomes somewhat more relevant to casual fans because of it.
- character - Although the Doctor's involvement is creative.
essential- Even if the ending doesn't need it to work at all.