Love in the Time of Plague

 is the first mission in the Red Dead Redemption Undead Nightmare DLC pack.

Story
Marston returns home on a stormy night with an uneasy feeling he can't quite put his finger on. John then inquires about Uncle's whereabouts, but Abigail was under the impression that John and Uncle had been together. She tries to assuage John's apprehension by making light of the situation and reminding John that Uncle can take care of himself. This does not, however, set John's mind at ease, and the family has dinner without Uncle.

After supper, John asks Jack about the book he's been reading. According to Jack, it's a book about monsters and he begins to relate a story of the ancient Aztecs and a plague-causing curse. Abigail dismisses it as nonsense and everyone goes to bed.

Later that night, when the moon is full, John and Abigail are awoken by Uncle coming into their bedroom. Uncle is covered in blood, sneering and growling. The old man makes a bee-line for John who grabs Uncle by the throat and beats him over the head with a nearby map. Despite only wearing his Union Suit, Marston goes to fetch his gun.

Meanwhile, Uncle revives and chases Abigail out of the house. He has already bitten her when John arrives with his gun.

Mission Details
To complete this mission the player must:
 * Kill Uncle.
 * Hogtie both Abigail and Jack.

Be sure to shoot Uncle in the head as body shots will not kill him. Abigail and Jack are easily subdued and the player should have no issues with them.

After the cutscene ends, the player should head to Blackwater.

Trivia

 * Most of the events in Undead Nightmare seem to take place between the missions "The Outlaw's Return" and "The Last Enemy That Shall Be Destroyed".