Time Lions

Twins Pearl and Patrick are no ordinary twelve-year-olds. They're geniuses hiding in plain sight, who pull heists all over the world to further their scientific and historical research. Their criminal activity, including grand theft auto, B&E and even espionage, has made them a regular nuisance to both the CIA and MI6. But it's all been worth it. They've finally achieved their greatest triumph: time travel. Pearl's Chrono-Loop can take the twins anywhere! Their first stop: ancient Egypt, where they even get to see King Tut!
But when they return home, they're arrested by TIME (The Interdimensional Misconduct Enquiry) a secret organisation charged with maintaining the timeline. Turns out Pearl and Patrick didn't invent time travel - that happened two hundred years ago! And what Pearl did in ancient Egypt - killing a mosquito - could have rewritten history as we know it if not for TIME agents stepping in.
Punishment for disrupting the timeline is normally 100 years in the Eternal Abyss. But TIME, impressed by the pair, offer them a chance to become agents. Unfortunately, they fail their entrance exam, and instead are banned from ever attempting time travel again. Pearl is infuriated and when she's offered another chance at time travel from a rival organisation, she can't resist. Too late, she realises she's been tricked and unwittingly plays a hand in replacing the timeline they know with a nightmarish scenario.
Now Pearl and Patrick must fix their mistake. But the only way to save the future is to go back to the past to enlist the true inventor of time travel for their help.