> Attempt to use the pen held in the sheathe as a key

You take the pen out of the sheath and rattle it around in the keyhole for a bit, but it doesn't do anything. Worth a shot, at least.

> Investigate upper right thing.

Based on how it feels, it's a wooden table. There is a photograph frame and a notebook on it, though without a light source of any kind you can't make out what either item contains. There is also a second locked chest, though this one is much smaller.