ST:TNG:80 - "Legacy" (Stardate: 44215.2) - this is the 6th episode of the 4th season of Star Trek: The Next Generation, the 80th episode to air overall. It is a historic episode because it surpasses the Original Series' 79 episodes length. In fact, there is an homage at the beginning of the episode with Picard saying in the captain's log that they "bypassed Camus II" to go to their emergency mission on Turkana IV. Camus II was featured in the last (79th) episode of the Original Series - "Turnabout Intruder".
Also, this episode delves more into Tasha Yar's past, since Turkana IV is the planet she grew up on. We meet her sister, Ishara Yar, who isn't what she seems.
Trivia note: you see the poker game again. Also, Data recalls the events to Ishara of the 1st season episode "Skin Of Evil" of how Tasha Yar was killed.
Also, this episode delves more into Tasha Yar's past, since Turkana IV is the planet she grew up on. We meet her sister, Ishara Yar, who isn't what she seems.
Trivia note: you see the poker game again. Also, Data recalls the events to Ishara of the 1st season episode "Skin Of Evil" of how Tasha Yar was killed.