"Livin' La Pura Vida" is the seventh episode of Season 31.
The Simpsons join other Springfield families on the Van Houtens' annual trip to Costa Rica, which they obviously can't afford. While there, Homer befriends Patty's new girlfriend, Evelyn, and Lisa tracks down the real reason the Van Houtens can go on this trip every year.
The episode starts off with Marge picking up Bart from his sleepover at the Van Houten Residence, Luann invites Marge and her family for their yearly trip to Costa Rica. Marge quickly speeds home to propose the vacation and rest of the family quickly accepts. Later that night, Lisa overhears her parents discussing how expensive the cost will get and starts becoming worried at the cost herself.
At Springfield International Airport, the Simpsons meet up with the Van Houten family, the Hibbert family, Chalmers and his daughter Shauna, and Patty and her new girlfriend Evelyn, to go on the vacation. Marge asks Homer to be nice to Evelyn for Patty's sake, while openly starts speak badly of Homer after what she heard from Patty. After arriving in Costa Rica, Lisa become even more worried about the expenses of the trip. Meanwhile, Kirk keeps track of all the expenses upfront and will divide the checks up at the end of the trip.
At dinner at the Van Houten vacation home, Homer and Evelyn discover that they have a lot in common. The next morning, Homer and Evelyn chose to stay at the home, while everyone else goes shopping. However, when everyone else returns to the home they find the two drunk and sunburned, having numerous monkey trashed the place. Marge is furious with Homer's behaviour, and makes him promise to behave for the reminder of the trip in order to get a perfect photo of them for their trip.
Homer and Marge are able to take a prefect photo of their vacation at the waterfall, but a wave from Evelyn's splash knock the phone into the water. At dinner, Patty blames a depressed Marge for making her girlfriend reduced to his level. Marge fires back at Patty by saying how Evelyn ruined everything for her and is a bad influence on Homer because she acts just like him, telling Patty she is "dating a Homer". Patty is horrified and abrupt ends her relationship with Evelyn that night.
Bart finds Lisa upset and reveals her financial worries to him, this makes Bart suggest they show their parents Kirk's expenses book. They sneak into Kirk and Luann Master bedroom for evidence, they don't have to worry about Milhouse since he ditched Bart for Dr. Hibbert's son J.J.. Underneath their bed, the two find what Lisa believes to be rare priceless artifacts. Lisa attempts to expose the Van Houten the stones the Van Houtens are selling back home to pay for their vacation every year at dinner, but Kirk tells her off, pointing out that they are just salt and pepper holders: they were meant to be a gift for the families who are staying at the vacation home.
The next morning the Simpsons chose to leave their trip and quickly given a bill by Kirk, after seeing the final amount Homer is shocked at the final amount, Lisa was right to be worried. In revenge for charging them extra for ruining their trip, the family sneak back into the home to get the salt and pepper holders but inadvertently discover a painting of the explorer Kirkedemious Van Houten who built the vacation house the Van Houtens own, and confront the Van Houten family making people pay for the trip with their own money while they get the house for free. In the middle of the commotion, Marge has a heart to heart talk with Patty, saying sorry for causing the break up between her and Evelyn. She tells that while Homer hates her, Evelyn loves her more than anything else in the world. Patty then agrees to restart her relationship with Evelyn.
Kirk bitterly refunds everyone their money back so they can live the vacation like they intended to. Homer wants to go back to the waterfall to retake the perfect photo of him and Marge, but she convinces him that their vacation is not about being perfect, it is about living in the moment, just as a reconciled Patty and Evelyn kiss on the zipline.