Fentress agreed to install a 'flood control system' at D's home for $ 900. D drafted a personal check payable to 'Fred Fentress--A-OK Plumbing' for $500. Fentress failed to appear on the date set for installation and Hodge telephoned him to announce the contract 'canceled.' D told Fentress that he would order his bank not to pay the check Fentress had been given. Hodge stopped payment that same day. Fentress presented the check at P, endorsing it as 'sole owner' of A-OK Plumbing, and obtained payment. D's bank refused payment to P. P claiming HDC status sued D, as drawer of the check, and Fentress for the amount stated. D moved to dismiss P's action under 3-305 in that P may be barred based on 'illegality of the transaction.' D contends that because Fentress was not a licensed plumber his promised performance under the contract gave rise to the requisite 'illegality' to bar P's claim for payment. D’s motion to dismiss was granted, and P appealed.