On October 17, 1941, Zell (plaintiff) wrote a letter to American Seating Company (American) (defendant) asking American if they were interested in Zell’s services to acquire defense contracts for American. The terms of Zell’s payment were a monthly fee plus a bonus based on the defense contract price. Zell later orally confirmed his terms of payment with American’s president. On October 31, 1941, American and Zell signed a written agreement reciting the terms they discussed except the contract omitted the bonus provision. American claimed they could not put that provision in writing, but assured Zell that the previous conversation was still the real contract. After Zell acquired defense contacts for American, American refused to pay Zell any bonus. Zell sued for breach of contract. The trial court granted American’s motion for summary judgment because the letter and oral conversation were inadmissible as parol evidence. Zell appealed.