Beguiling the Baron by Elizabeth Keysian

Beware reclusive barons. They are more hot-blooded than you’d expect . . .
A man who lurks day and night in an eerie tower must have something to hide. So thinks Galatea Wyndham, governess to Lord Ansford’s love-starved young daughter. Galatea’s new employer is objectionable, stubborn, great-hearted, handsome and, curse it, well worth saving from himself.
He proves her right with some shocking physical encounters, adding tinder to the blaze of her growing love for him. But just as the barriers between them are crumbling away, the tower crashes down.
With Lord Ansford inside it.