Kris reluctantly allows Kim to take over the annual Christmas Eve party; Khloé must come to the rescue when North's hamster dies; Kris tries to understand the unconventional relationship between Kourtney, Scott and his girlfriend.

After an uncomfortable confrontation with her ex at True's first birthday, Khloé must figure out how to coexist with her ex. Kim accuses Kourtney of copying her style. Kim searches for answers regarding a frightening medical diagnosis.

Kim gives the world an intimate look into the busiest week of her life as she prepares for the birth of her fourth baby, stars in a music video with Paris Hilton, and heads to the Met Gala. Kourtney feels violated when she realizes someone close to her family has been stealing from her.

When Tristan starts showering Khloé with gifts, she worries his grand gestures are an effort to win her back; after Kim and Kourtney learn that people are being sickened by toxic waste in a nearby community, they vow to help.