Wesley and Geordi are involved with an experiment in engineering as the Enterprise takes on new crew members at Starbase 133. Dr. Crusher welcomes on board an old friend, Dr. Quaice who seemingly disappears overnight without a trace. In fact, no one, including O'Brien who beamed him up, remembers seeing him and there is no trace of his existence anywhere in Starfleet. As the crew begins to vanish, also without a trace, Dr. Crusher struggles to convince Picard that something is wrong and comes to doubt her own sanity.

Producers: David Livingston, Lee Sheldon
Director: Cliff Bole
Writer: Lee Sheldon

Guest Cast:

Bill Erwin (Dr. Quaice)
Erik Menyuk (Traveler)