In the fairly near future, all of human history is now stored on a single monolithic memory bank: Humanity's History Hard Drive. But that sucker is just about full.
The all-powerful Council has tasked Rebecca Charytan and Zachy Hennessey - two apparently equipped workers from the Ministry of Memory - with wading through every single day in the calendar year, pitching two historic events from that date against each other to see which stays, and which gets deleted - FOREVER.