Yale law professor Ian Ayres works through Wood v. Lucy, Lady Duff-Gordon, a staple contracts case, as part of his course American Contract Law. The case involves an exclusive endorsement deal for the fashion designer Lady Duff-Gordon, who argued the agreement lacked mutuality of obligation because it did not explicitly require her marketing partner to do anything in return. Ayres uses the case to explain how Judge Cardozo found an implied promise to use reasonable efforts, turning what looked like an illusory contract into an enforceable one. The lecture sits within a unit on consideration doctrine and its substitutes, showing how courts read obligations into commercial contracts even when the text is silent. Ayres walks through the reasoning step by step, connecting it to the broader problem of mutuality in one-sided-looking agreements. Ten minutes of focused case analysis aimed at students following the course sequence.