Tris is picking up her notes at the end of a lecture, when she spots a purple book on the desk next to her. The other students are already leaving.

She would normally ask if it belonged to anyone else, but it is clearly and obviously extremely magical, aura glowing with power. She looks at it again. Blinks, dampens the light. This…is not something she should leave lying around. Maybe it belongs to an exceedingly careless student, but if wanted no one else to look at it they should have kept better track of it. 

She gives a cursory check for any tracking spells and obvious curses, finds none, and picks it up to look into at home, where she has space, tools, and backup if something goes exceedingly wrong.