["Oh great. There was a big spider in my room, so I went to get something to scoop him up with (or flatten, I hadn't decided between the two yet). I come back and he's disappeared.", "oh oh, so now you don't know where your enemy is hiding.  Sounds scary.", "It's scary and annoying because now I have to systematically check every inch of my room because I'm definitely not sleeping here with that big ol spider somewhere in my room!"]
How annoying, but would be wise imagine it jumping on you while you sleep.
There was this giant spider in my room. I'm afraid of spiders. I went to get something to get it with, and I came back. The spider is now missing.