NOT KNOWwithout that person knowing about it 不为某人所知的
Unbeknown to him, his wife had been trying to phone him all morning.
他哪里知道,妻子一上午都在给他打电话。
Examples from the Corpus
unbeknown to somebody• Unbeknownst to the public, he was involved in covering up the scandal that was to rock the nation.• Unbeknown to me, Denise had her own plan.