Kennedy is out for lunch, and she's allowed to be off on her own.  She's not supposed to cross the space between those two buildings, but she hasn't; she's gone over one of the buildings.  (She's allowed to do this sort of thing, as long as no adults catch her, including by noticing dust on her outfit or tangles in her hair.  They encourage it, even.)

She's very good at climbing, so she has a solid fifty minutes before she has to be back for her math lesson.

Unfortunately, on the way to her favorite bistro, a snake with a mirror for a face appears, and eats several other people, like that, they just disappear - and then it eats her, and she's somewhere else.

...She's surprised and glad to be alive, but she doesn't think she's going to be back in time for her math lesson, let alone with perfectly innocuous grooming.