The Masquerade | Brenda Joyce

From the back cover:

As a child, shy, bookish Elizabeth Anne Fitzgerald loses her heart to the dashing young lord, Tyrell de Warenne. Although she is well aware that he is the heir to an earldom and utterly unattainable, Lizzie secretly worships him for years. And one fateful evening—the night of her first masquerade ball—she is stunned when he suggests that they rendezvous at midnight. But then fortune takes a maddening turn and Lizzie is thwarted from ever meeting Tyrell. Lizzie is certain such an opportunity will never arise again, but that night is only the beginning...

Tyrell de Warenne is shocked when, two years later, Lizzie arrives on his doorstep with a child that she claims is his. He remembers her well—and knows that it is impossible that he is the boy's father. What is this game she is playing...and why? Is Elizabeth Anne Fitzgerald a woman of vast experience, or the gentle innocent he had believed her to be? Tyrell quickly decides he will play her game and he claims the child as his own—determined to uncover Lizzie's lies. But neither scandal, deception nor pride can thwart a love too grand and passionate to ever be denied...