Passanger's destination yet to reach

He's just a driver. No dreams, no destination of his own, just other people's addresses and a paycheck at the end of the night.
She's just a passenger. Or that's what she wants him to believe.
One ride. One almost-crash in the middle of nowhere. One girl standing in his headlights, soaking wet, with nowhere for the water to have come from.
He should've dropped her off and forgotten her by morning. Instead she vanishes mid-route, leaving behind nothing but a diary so waterlogged the ink has started to bleed, and a silence from her family that makes no sense at all.
No one is looking for her. No one even knows she's missing.
Except him.
And the more he searches, the more he realizes she was running from something long before she ever got into his car, something with teeth, something with a clock attached to it. Ninety days, and counting down, though counting down to what, he doesn't yet understand.
She's not lost. She's drowning, in more ways than one, and he's the only one who noticed she was ever gone.