I always find this the weakest of the two-part episodes. It is a pretty good story, marred by some flaws of logic. I shall simply list some of them:
o It was previously established that *only* Data's doohickey could provide the needed sensitivity to allow for the phase change. That was a crucial point, because it was the *only* reason that Picard allowed Data to go on the mission at all. Now, all of a sudden, Geordi can build another one, no problem. If Geordi was able to build one, why didn't they try that *the first time*, instead of risking Data?
o When the landing party is assembled to go after Data, its makeup makes no sense. The initial party is supposed to be Riker, Geordi, Worf, Crusher, and Troy. OK, Riker to lead the mission, makes sense. Geordi to run the technical gadgetry, OK. Worf because who knows what dangers they'll encounter, makes sense. But Troy and Crusher? Seriously? Troy and Crusher? Because Data's going to need a doctor? Or a *counselor*??? Wouldn't a couple of security guys make more sense?
o But it gets worse. Then Picard decides to insert himself into the mission. So who does he send back to the ship? The useless Troy or Crusher? No. The now useless Riker-- (Picard himself will now obviously lead the mission)? No. Worf. The one guy it would make sense to bring when you're going up against some unknown, unseen aliens. But this is beyond just a bad assessment of the away team. Consider *the ship*. If Picard goes on the mission, *and* Riker, *and* Geordi-- and Data's already missing-- you now have *every* top officer missing from the Enterprise. When Worf is sent back to the ship-- he's actually *in command*! He's the ranking officer! You're up against mysterious aliens of unknown and apparently hostile intent, and you're going to leave the flagship of the Federation under the command of a mere Lieutenant? In the whole rest of the series we never see Worf in sole command of the ship (yeah, once he sat in the chair while Picard was waiting in the next room). *** Wouldn't it have made VASTLY more sense to send Riker back instead of Worf ***?
(Of course, these flaws stem from lazy writing. The writer, already knowing what they were going to encounter in San Francisco, had hand-picked the landing party in a way that Picard could not. For instance, they needed Crusher to discover the truth about the plague, and they needed to *not* have Worf, so as not to need to explain his Klingon appearance to the 19 century folk)
o The entire, problematic appearance of the landing party in 19th century San Francisco is completely skipped over. How did *all five* of them suddenly appear there, in Federation uniform, without causing anyone to notice or be concerned? Where did they get their 19th century clothes from? And if they were able to get clothes, why weren't they able to get rent money? Crusher was working as a nurse, that should have provided enough income to afford their one room.
o Riker asserts that if you were a time-traveling species that wanted to kill humans without attracting notice, that you'd go to some plague-ridden time. Which makes sense. So wouldn't 12th century Europe-- at the time of the actual Black Plague-- make much more sense than 19th century San Francisco? I think history provides *tons* of better choices than 19th century San Francisco. How about the Irish potato famine? World War II Stalingrad?
o Why on earth didn't Data and Guinan take Twain into their confidence? Guinan knew Twain, knew him to be an intelligent and sensible man, why wouldn't they trust him with the truth? Telling him lies and stories was obviously only making him more suspicious and paranoid.
o Um, why is Twain portrayed as such a frothing Luddite? I can find no evidence that the real Mark Twain was one. In fact, he was an early adopter (for a while, at least) of that new-fangled invention of the era, the typewriter.
OK, so far these are all somewhat minor. But this is the big one:
o Explain to me how it makes any sense at all that the *only* food these aliens can eat is human neuro-chemical energy. *Human*. Vulcan or Klingon won't do. Has to be human. The humans have never even *heard* of these people, how do the aliens even *know* about humans? How does a race on one planet evolve such that its only source of food comes from beings on a planet a zillion light years away? And all this, to get what? "electrochemical energy"? What's so unique about our electrochemical energy? It's really just chemical energy. And not even that much of it, how much voltage is there in the human nervous system? How is this not something they could create artificially? Or for that matter, why not just use animals? Humans differ from animals in the complexity of their brain structure, not in the fundamentals of neurochemistry. There's no good reason why the aliens couldn't eat cow energy. This whole we-must-eat-human-energy thing ***makes no sense***.
o It was previously established that *only* Data's doohickey could provide the needed sensitivity to allow for the phase change. That was a crucial point, because it was the *only* reason that Picard allowed Data to go on the mission at all. Now, all of a sudden, Geordi can build another one, no problem. If Geordi was able to build one, why didn't they try that *the first time*, instead of risking Data?
o When the landing party is assembled to go after Data, its makeup makes no sense. The initial party is supposed to be Riker, Geordi, Worf, Crusher, and Troy. OK, Riker to lead the mission, makes sense. Geordi to run the technical gadgetry, OK. Worf because who knows what dangers they'll encounter, makes sense. But Troy and Crusher? Seriously? Troy and Crusher? Because Data's going to need a doctor? Or a *counselor*??? Wouldn't a couple of security guys make more sense?
o But it gets worse. Then Picard decides to insert himself into the mission. So who does he send back to the ship? The useless Troy or Crusher? No. The now useless Riker-- (Picard himself will now obviously lead the mission)? No. Worf. The one guy it would make sense to bring when you're going up against some unknown, unseen aliens. But this is beyond just a bad assessment of the away team. Consider *the ship*. If Picard goes on the mission, *and* Riker, *and* Geordi-- and Data's already missing-- you now have *every* top officer missing from the Enterprise. When Worf is sent back to the ship-- he's actually *in command*! He's the ranking officer! You're up against mysterious aliens of unknown and apparently hostile intent, and you're going to leave the flagship of the Federation under the command of a mere Lieutenant? In the whole rest of the series we never see Worf in sole command of the ship (yeah, once he sat in the chair while Picard was waiting in the next room). *** Wouldn't it have made VASTLY more sense to send Riker back instead of Worf ***?
(Of course, these flaws stem from lazy writing. The writer, already knowing what they were going to encounter in San Francisco, had hand-picked the landing party in a way that Picard could not. For instance, they needed Crusher to discover the truth about the plague, and they needed to *not* have Worf, so as not to need to explain his Klingon appearance to the 19 century folk)
o The entire, problematic appearance of the landing party in 19th century San Francisco is completely skipped over. How did *all five* of them suddenly appear there, in Federation uniform, without causing anyone to notice or be concerned? Where did they get their 19th century clothes from? And if they were able to get clothes, why weren't they able to get rent money? Crusher was working as a nurse, that should have provided enough income to afford their one room.
o Riker asserts that if you were a time-traveling species that wanted to kill humans without attracting notice, that you'd go to some plague-ridden time. Which makes sense. So wouldn't 12th century Europe-- at the time of the actual Black Plague-- make much more sense than 19th century San Francisco? I think history provides *tons* of better choices than 19th century San Francisco. How about the Irish potato famine? World War II Stalingrad?
o Why on earth didn't Data and Guinan take Twain into their confidence? Guinan knew Twain, knew him to be an intelligent and sensible man, why wouldn't they trust him with the truth? Telling him lies and stories was obviously only making him more suspicious and paranoid.
o Um, why is Twain portrayed as such a frothing Luddite? I can find no evidence that the real Mark Twain was one. In fact, he was an early adopter (for a while, at least) of that new-fangled invention of the era, the typewriter.
OK, so far these are all somewhat minor. But this is the big one:
o Explain to me how it makes any sense at all that the *only* food these aliens can eat is human neuro-chemical energy. *Human*. Vulcan or Klingon won't do. Has to be human. The humans have never even *heard* of these people, how do the aliens even *know* about humans? How does a race on one planet evolve such that its only source of food comes from beings on a planet a zillion light years away? And all this, to get what? "electrochemical energy"? What's so unique about our electrochemical energy? It's really just chemical energy. And not even that much of it, how much voltage is there in the human nervous system? How is this not something they could create artificially? Or for that matter, why not just use animals? Humans differ from animals in the complexity of their brain structure, not in the fundamentals of neurochemistry. There's no good reason why the aliens couldn't eat cow energy. This whole we-must-eat-human-energy thing ***makes no sense***.