The context of the following conversation is Austin was walking up the stairs then when he got to the top he remembered something so he traced back down the steps.:
Austin says I need to get my shirt upstairs..
The friend responds Okay, I am waiting..
Austin responds Oh, I can't find the key to my room..
The friend responds I think it fell off when you were climbing the stairs..
Austin responds Let me trace it back..
The friend responds Be quick, we have to go..