You should watch:

Where Silence Has Lease

This was episode number 2 of season 2.

The following characters appeared in this episode:

(voice)Nagilum

(voice) (uncredited) Enterprise Computer

Captain Jean-Luc Picard

Chief Miles O'Brien

Counselor Deanna Troi

Commander Wiliam T Riker

Doctor Pulaski

Haskell

Lieutenant Geordi La Forge

Lieutenant Worf

Lt Commander Data

Wesley Crusher