The House of Spies by Warwick Deeping

Nance was awakened that night by the sound of some one walking on the stone-paved path below her window. She sat up in bed with a fluttering of the heart, wondering whether the footsteps were the footsteps of her father, or whether Jeremy had ridden over late with news.

She was about to slip out of bed when she heard voices on the terrace. There appeared to be several men talking together in undertones. Then came the crash of glass being broken, as though they were battering in one of the lower windows.