The First Task

Temporal Guardian Hethress's focus was ruined by an alarm going off. She was overcome with anger and stormed out to find the source. I was so close to a breakthrough. A new insight into The Prophecy was within my grasp! Another three to four weeks and I'm sure I'd have it.

Those thoughts were replaced by cold horror when she found the source of the noise. This alarm had not gone off for at least three centuries and it meant only one thing: history had been altered. She flew to the Archives at once.
* * *
Hethress addressed the librarians and acolytes from her dais, her voice booming. "We have confirmation that someone or something has altered the past. Your first task is to find out what has changed. Split into pairs to compare the text of each history book in the Vault with the copies in the general library. DO NOT REMOVE THE ORIGINAL FROM THE VAULT. Anyone who does so shall be executed.
"Read every line of every book and look for any differences, no matter how small. Bring these differences to me when you find them. Now get to work."