Betrayed by Love — Carolyn Keene

NANCY'S JOINED A WEDDING PARTY IN WHICH SOMEONE HAS TAKEN A DEADLY VOW.
Nancy's old friend Angela Chamberlain is getting married, and Nancy's come to her family's opulent Long Island estate to be a bridesmaid. But love and money can be a very volatile mix. It becomes clear, before the ink is dry on the invitations, that the date is set for danger and that Nancy will have to stand up for Angela in more ways than one.
The romance between Angela and her fiance has suddenly taken an ugly turn. Sinister rumors, hints of scandal, and whispers of betrayal have begun to surface. With them come a series of near fatal "accidents" culminating in attempted murder. If Nancy doesn't uncover the culprit soon, Angela's dream wedding could end in a nightmare!