Started by time

How to go from modern Washington to the distant Chicago of 1893? For Kate, the impossible became real.
It turns out that the strange medallion of her grandmother is nothing more than the key to the headquarters of the chronos - the organization of historians from the future traveling in time. Soon, Kate discovers that reality has changed and her parents no longer exist, and she remained alive only thanks to the protection of the key. Someone killed Kate"s grandmother when she was in the nineteenth century. The girl should go into the distant past and find out how to prevent terrible consequences.
But if everything works out, the guy she likes will never remember her again. Will her movements to the fate of the whole world affect?