Once she gets herself to a certain acceptable level of dryness, YT heads back into the bedroom - still wearing the towel - and goes to the desk. In Milliways the desks always come with a pencil and notepad in the drawer: she gets these out and starts to sketch a rough map.

There are three floors in the building she left on the other side of the Door, and it's got a central courtyard: used to be some kind of office. She pencils in the rooms and dimensions - working it through in spite of the fact that she's having trouble keeping her eyes open - and ends with putting an X in a room on the second floor and writing "we are here."

She then finds herself unable to suppress the urge to yawn and stretch, which is a little embarrassing for all that Max warned her about it.