As children, we are told to wish on a shooting star though unbeknownst to us the "star" was just a bit of space debris.
Yet unbeknownst to her (or the reader), Aragorn has already pledged himself to Arwen, Elrond's daughter, a half-elven lady as far above him in station as he is above Eowyn.
Unbeknownst to Jean, Mathew Knowles - Beyonce's father and now former manager - heard the song and decided he wanted it for his daughter.
Unbeknownst to the average 4th of July and New Year's celebrators, however, fireworks can often be purchased online cheaper than they can be bought from local suppliers.
A friend there invited me out to dinner one night with some friends of his who were over from the US and, unbeknownst to me, owned Baskit.