Lam, who runs an art gallery, exhibits for sale a number of artworks by well-known American painters. Nat visits the gallery on 1 October, and is interested to purchase a piece entitled "Yard No. 56" by Mark Rothko with a price tag of HK$ 1.5 million. Nat's offer of $1.2 is rejected by Lam, who says, "The best price I can give you is $1.4 million." Nat says he needs "a couple of days" to think the matter over. Lam says, "Alright, but do decide soon. It is not often that a Rothko of this quality is available for this price." Lam provides Nat his business card, while Nat provides Lam his contact details. On 3 October, a customer (Randall) indicates that he is willing to pay the asking price of $1.5 million. Lam makes a telephone call to Nat, but is channeled to Nat's voice message recorder instead. Lam leaves a message indicating that the Rothko is no longer available. Lam then sells the painting to Randall. Nat does not access his voice messages. On 4 October at 10am, Nat sends Lam an email message stating that he 'accepts Lam's offer of $1.4 million'. Advise Nat.