"A shower counts as getting wet, not as swimming," Derek says with a laugh, watching as Thomas moves around in the water. "I'll teach you how at the swimming hole. It'll be easier there. I do a mean doggy paddle."

He winks teasingly, but his expression grows more concerned as Thomas speaks. Curiosity gets the better of him, and he can't help but to ask. "What happened to the world where you're from?"