Book excerpt: Time travel. It's dangerous, traumatic, a high-risk pursuit. It's also the most thrilling thing you'll ever do. Sam Winterson has gone missing in time. One of his heists has gone seriously wrong, and if he doesn't surface soon, his enemies will take their revenge on his mother. As the time traveler who rescues lost time travellers, I am the only one who can help. But there are three problems. Nobody in my daily life - including my boyfriend Delaney - knows that time travel is possible, except... ... my twin sister, Luna, who refuses to take on this mission for me, because.. Sam is my ex for a reason. But does that mean I should leave him to die?