(out of 5)
|* * * *|
The crew on the Voyager are getting exchanged one by one with members of an unknown alien race. The aliens profess to have no knowledge of how they ended up on Enterprise or what happened to the crew members. At the rate the exchanges are happening, in less than a day all of Voyager's crew will be gone. Something sinister is going on below the surface of these seemingly accidental occurrences.
The episode combines the 'ship in peril' theme with a investigative mystery to deliver an engrossing episode. One of the better ones in an otherwise dismal third season.