Star Trek: The Next Generation – Code of Honor [1.3]

Lutan, the leader of a planet that has access to a critical vaccine, kidnaps Tasha Yar and claims her for his wife, leading his current wife Yareena to challenge her to a battle to the death. 

Star Trek: The Next Generation – The Naked Now [1.2]

The Enterprise crew become infected with a neurological condition which leads to diminished self-judgment, that has already led to the deaths of a scientific investigation crew.  Infected, Wesley Crusher takes over engineering