since it is the middle of flu season, the school closes early. Since Susan is studying, Greg has to call Frank from work to pick him up, which Frank is not happy about. Susan then announces to the family that they will get "domestic help" with a maid named Isabella, since both parents are busy, who will help take care of the kids after school. However, instead of doing her responsibilities, Isabella secretly spends her time watching television and eating the Heffleys' snacks, leaving Greg and the rest of the family with extra work. Worse, Greg finds a pantyhose sock in his bed, showing Isabella has been napping there. Meanwhile, Greg gets ready for a dentist appointment, but Frank takes Greg to his dentist, Dr. Salazar Kagan (who takes oral health seriously) because he thinks Greg is too old for his usual dentist, Rachel. As Dr. Kagan cleans his teeth, Greg accidentally bites Dr. Kagan's finger while having X-rays taken, which results in him wearing headgear for his overbite. The next day, Greg loses his headgear and when he comes back home from school, he finds Manny wearing it. Not wanting to let his social life get ruined, Greg vows never to wear the headgear again regardless of what the dentist says. Later, Greg finds out that the school is having a lock-in for Friday night, in which participants would sleepover and spend time doing activities. Greg signs up, but when he arrives, he is shocked that 90% of the crowd is all boys, and even worse for him, Rowley is also there as well. During the sleep period, the boys make multiple attempts to leave the school building after their phones are confiscated by the chaperones and are unable to contact their parents. However, at around 2:00 AM, most of the parents arrive at the school, angry because the kids weren't able to answer their cell phones, sending them all into a panic. As a result, most of the kids go home early, leaving Greg and Rowley behind as the only kids without cell phones. The following week, Greg becomes sick due to a lack of sleep at the Lock-In. Although he has faked sick in the past, Susan takes his temperature and agrees that he genuinely is sick. She leaves him with Isabella. Greg later falls asleep but wakes up due to the noise from downstairs. He looks