Inexplicably, the Voyager crew begins switching places with members an alien race, one by one. As one crewman vanishes, a Lyrian appears on board, wondering how s/he got there. Over time, there are more alien guests than remaining Federation members. Capt. Janeway's gut reaction proves correct: this isn't an accident, it's by design, and the entire crew soon finds themselves in a combination prison/zoo, but they aren't alone. They have neighbors, and environmental factors prove to be on their side.
—statmanjeff