The listing, Star Trek The Next Generation: 2 paperbacks: "Sins of Commission" and "Masks" has ended.
Plot summaries from Goodreads:
Sins of Commission: "While on a mission to save the planet Lessenar from environmental collapse, the crew of the U.S.S. Enterprise becomes entangled in a web of treachery and murder.
When a member of a strange, emotion-casting race is killed on board the ship, all evidence points to Lieutenant Worf and one of his oldest friends.
Soon the crew of the Starship Enterprise is crippled by an emotional onslaught as the surviving aliens respond in anger and pain to the death of their comrade.
Worf must overcome this alien influence and find the true killer with the destruction of the Starship Enterprise, the survival of Lessenar, and his Klingon honor hanging in the balance."
Masks: "The "U.S.S. EnterpriseTM journeys to Lorca, a beautiful world with a feudal culture where the inhabitants wear masks to show their rank and station. Captain Picard and an away team don masks of their own to begin a quest for the planet's ruler and the great Wisdom Mask that the leader traditionally wears. Their mission is to establish diplomatic relations. But shortly after transporting, Picard and his party lose contact with the ship, and Commander Riker leads a search party down to the planet to find them.
Both men, are unaware that their searches, indeed, the ship's entire mission are part of the plan of a madman, a madman who is setting the stage for a trap that will ensnare both "U.S.S. Enterprise landing parties, and leave him to seize control of the awesome Wisdom Mask as well as the planet Lorca itself."
Paperbacks in good condition, smoke free home, will add GIN if requested before the first bid, good luck bidding!