Stan sold goods to Bill in good faith, believing him to be a principal. Bill in fact was acting as agent for Nancy and within the scope of his authority. The goods were charged to Bill, and, on his refusal to pay, Stan sued Bill for the purchase price. While this action was pending, Stan learned of Bill's relationship with Nancy.

Nevertheless, thirty days after learning of that relationship, Stan obtained judgment against Bill and had an execution issued that was never satisfied.

Three months after the judgment was made, Stan sued Nancy for the purchase price of the goods. Is Nancy liable? Explain.