You should watch:

Where No One Has Gone Before

This was episode number 5 of season 1.

The following characters appeared in this episode:

Argyle
Ballerina
Captain Jean-Luc Picard
Counselor Deanna Troi
Commander Wiliam T Riker
Crewmember
Doctor Beverly Crusher
Kosinski
Lieutenant Tasha Yar
Lieutenant Geordi La Forge
Lieutenant Worf
Lt Commander Data
The Traveler
Wesley Crusher
Yvette Picard