Key

Victor wondered who had knocked on his bedroom door, but when he looked both ways down the corridor, he saw no one.

Immediately, Victor wondered who could have been so quick and quiet to knock on the door and disappeared before it opened. Victor then bent down to pick up the object that had been left at the foot of the door. It was a small silver key. Intrigued, Victor examined the key more closely, turning it over in his hands. There was a symbol embedded in the head of the key, a symbol that looked like a prism.

"A key..." he muttered to himself. 

He knew that this was probably not a simple coincidence; someone had left this object there on purpose right after knocking on his door, and the question was who and why.