The Enterprise plays host to some Ullians, a race of telepaths who have the ability to probe others' minds and bring to the surface long-buried memories that are lying dormant in a subject's head. The Ullians do this to help people and for reasons of historian scholarship. But then strange things begin to happen. Troi experiences a memory with Riker that suddenly goes awry. One of the Ullians, named Jev (Ben Lemon), puts himself in Riker's place in one of Troi's memories and assaults her. The memory invasion leaves her in a coma. When Riker and Crusher attempt to get to the bottom of the coma mystery, they also end up in comas. The story itself makes no mystery of the villain; the teaser ends with an ominous shot of Jev that has no purpose other than to make him look suspicious.
Here's an episode that tries to deal with some challenging, more grown-up subject matter that is somewhat less ... shall we say, sanitized than your typical Trekkian fare. It does this while trying not to step for a moment outside the boundaries of family-friendly TNG that could air at any hour (or TV-PG, in the parlance of our post-1996-American-TV-ratings-system times), despite the fact that an implied sexual assault is at the center of the plot. If that sounds like a paradox, it is. The result is an episode that could've been edgy and psychologically intense (and at times comes close, within its predefined constraints) but in the end sort of comes off as a compromise. To put this in the terms of the TOS mantra of Using Sci-Fi Metaphors to Tell Stories We Otherwise Couldn't Get By the Censors: If memory invasion is supposed to a metaphor for rape, it's odd that the metaphor then includes an actual (well, kinda-sorta implied) rape.
The idea of using a person's memories against them, for the sake of psychological terror, is intriguing. (Crusher ends up in a coma when she relives a twisted-around memory of her husband's death.) And some of the dreamlike atmosphere here is suitably intense. This episode could've worked.
But the last act falls apart when Jev — who believes he has already gotten away with the crime by framing his father Tarmin (David Sage) for it — goes to Troi's quarters and then tries to attack her all over again, this time physically. It just doesn't make any sense — unless Jev is so obsessed with Troi he has completely lost his mind. Why would he go to the trouble of turning his mind-rape spree into a frame-job only to then out himself as the perpetrator? This is just a sloppy way to tie things up with action rather than dialogue — and it's unnecessary too, since Data and Geordi solve the case with their own investigation.
I also could've done without the episode's preachy final scene, which has dialogue that basically says humans (unlike Ullians, apparently, who are condescended to here based on the actions of one person) are so perfect now that there's apparently no such thing as violence as extreme as rape anymore, which flies in the face of common sense. This scene is also a clear violation of the show-don't-tell rule. "Violations" shows and then tells, just in case you didn't get it.