Sam tapped the dinosaur book. “Millions of years ago feels like words with no picture,” Sam said, tracing a line of huge numbers with one finger. Maps made sense. Roads, rivers, rooms—you could trace them. But time was slippery and huge. It would not stay still on a page.

Ren bent over the table, his grin growing. He pulled a scrap of paper close and tucked his pencil behind one ear. “Then we won’t keep it on a page,” he said. “We’ll make a map big enough to walk.”