You're a time traveler, but an unwilling one. You get pulled around to wherever you need to be. You have no say in the matter, it is all random.
You always have a partner who shows up first in whatever period in history you are needed. You're "chained" together, you always end up in the same place. Drawn to each other...and the thing that needs fixing.
Someone who doesn't belong in the time you've been thrown into has committed a crime that never should have happened. It has created a paradox and time is slowly falling apart. A paradox is an open wound in time and as it festers, awful, unmentionable things start to get in.
You've got to solve the crime, find the person who doesn't belong, and send them back to their own time. If you fail, time gets broken and you start all over. If one of you dies...you start all over. Time will keep skipping like a broken record until you get it right...or reality completely crumbles. No pressure!