Somewhere in Time by Cynthia Luhrs

She’s a 21st-century scientist. He’s a medieval lord with a heart of iron. Their love was never meant to be… but history has other plans.

Beth Anderson would rather dissect chemical reactions than endure another awkward date. But when a lab explosion hurls her to 15th century England, she’s got bigger problems than her nonexistent love life… like surviving in a world where her science looks like sorcery, and one wrong step could have her facing charges of treason.
Lord Baldwin Devereux doesn’t trust the strange, sharp-tongued woman he finds in the woods. But her brilliant mind and infuriating defiance intrigue him as much as they unsettle him. And when Beth’s “miracles”, sterilizing wounds, exploding fountains, predicting the future, draw the queen’s notice, Baldwin will risk everything to keep her safe.

As danger closes in, she has to decide… return to the future she knows… or stay with the man who’d burn the world down to keep her.