Tidewater. Doctor Who Season Four, with major spoilers for 4x08 and 4x09.
Fic below the cut.
"The dragons are a myth," she says. Another chunk of the wall falls in, rolling past her, with a great grinning lizard's head at the top. She scowls at it. "They're just a legend. This is a research site, not a fairy tale."
"Oh ?" he asks.
They run.
(
This fic contains major spoilers for characters and situations in 4x08, Silence in the Library. If you're staying unspoiled, don't click. )