Khloé invites her ex to True's first birthday party. Khloé decides to throw Kourtney a birthday party, but Kourtney's anxiety about turning 40 threatens to ruin the celebration. Kim receives a devastating medical diagnosis that could change her life.

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.

Scott feels under pressure to make sure both Kourtney and his girlfriend Sofia are happy on a family trip to Finland.

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.

After the birth of her son Psalm, Kim plans a surprise vow renewal ceremony; when Kourtney's friends can't get along on a girls trip to Turks and Caicos, she must assert herself to salvage the vacation.

Khloé's ex-husband Lamar releases a memoir; an old rumor resurfaces and Kris worries that it will spark a fight between her and Khloe; Kim is nervous to speak at a live press conference at the White House.

Kris is furious when some slanderous rumors circulate on the 25th anniversary of her friend's murder; Kim struggles to disconnect from work while on a trip to Costa Rica; some of Khloé's past insecurities resurface when she attends her first prom.

Kim and Kourtney plan a joint birthday party for their daughters; Kris is concerned about some of Khloé's obsessive behavior; after criticism over the name of her shapewear line, Kim faces a difficult decision about the future of her company.

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.

Kim and Khloé are furious that Kourtney is hiding aspects of her life from the cameras and attempt to fire her from the show; Kim helps a young man recently out of prison with his future.

Kris takes the family to Wyoming to ease recent tensions and strengthen their bonds, but her plan backfires when the girls start fighting on the trip; Kendall is excited to spend some much-needed bonding time with Kylie.