You should watch:

Future Imperfect

This was episode number 8 of season 4.

The following characters appeared in this episode:

(credit only)Ensign Wesley Crusher
(uncredited)Barash
(voice) (uncredited) Enterprise Computer
Captain Jean-Luc Picard
Counselor Deanna Troi
Commander Wiliam T Riker
Commander Tomalak
Doctor Beverly Crusher
Gleason
Jean-Luc Riker/Ethan
Lieutenant Worf
Lt Commander Data
Lt Commander Geordi La Forge
Minuet
Nurse Alyssa Ogawa
Transporter Technician Hubbell
Transporter Chief