Vera, the Medium.

Vera, a woman of questionable character places a wager that she will be able to destroy a happy marriage and inveigle the husband into becoming her lover. She succeeds to the extent of a midnight tryst in the family's home, witnessed by the couple's 12-year-old daughter. Her resolve weakened by the child's piteous pleas, Vera deliberately loses the wager, freeing the sadder-but-wider husband to return to his forgiving wife.