Star Trek: The Next Generation - 4x18 - Identity Crisis

    Years ago, Geordi was part of an away team, investigating the disappearance of everyone from a research station.  Now, almost everyone who was part of that away team have been acting strange, and eventually disappearing.
    This is an unusual episode, since it centers on Geordi, but it isn't an engineering related plot.  It's one of the medical mystery episodes.  It also doesn't use the other characters too much, which makes it seem like something is missing.  Even Picard doesn't do much in this one.
    The direction that the episode takes is a little far-fetched.  An alien that reproduces by rewriting a host's DNA?  The brood changes that are needed aren't as plausible.  The moment where we're supposed to discover that there's an invisible life form on the planet doesn't work well.  The shadow isn't obvious at all, and this just leaves the viewer puzzled about what it is that we're supposed to be seeing.
    By the end, the story is kind of fun, but something isn't right about it.  It doesn't stand out in my memory very well.