After a days work of chores, the Madrigals gathered for dinner. It was supposed to be a normal night, well as normal as a night can get for the Madrigals. But everyone was surprised by Mariano's proposal to Delores!
They had only been dating for nine months, but they were madly in love and were ready to get married. Delores said yes, of course and obviously something as important as a proposal needed to be celebrated with a party!
That had ruined Camilo and Mirabel's plan, but they were not going to bring Delores down on her big day.
Afterwards, Abuela was making her rounds of the casita to make sure everyone was asleep so everyone could wake up early to do their chores. Mirabel had snuck and hid in Camilo's room without being detected by Abuela. Camilo pretended to be asleep for the minute, maybe a minute in a half that Abuela checked to make sure he was asleep, and then shot up and gave Mirabel the all clear so she could come out of hiding.
Abuela needed a taste of her own medicine, so Camilo came up with a plan. Mirabel still could not see past Abuela's mentally abusive actions because she was raised thinking Abuela was always right, and to listen to Abuela all of her life, and since "she didn't get a gift" she always felt the need to help the family and impress Abuela in order to feel like a part of the family.
Mirabel wanted the prank to be a fun thing that everyone laughs at except Abuela, but Camilo found that difficult seeing as he wanted to treat her the way she treated everyone else.
Mirabel came up with a plan similar to Camilo's plan, but more harmless.
They decided to execute their plan the next morning.