"It looks like rain. You'd better stay in, Willie," warns Peter dashing out to mail the letter inviting Amy to his birthday party, and the storm--lowering clouds, explosive lighting, wind and water and glistening sidewalks--is as vital here, transforming the look and feel of the city, as the snow in The Snowy Day. The wind blows the letter out of his hand, almost to Amy running toward him, and he knocks her down trying to get it away and into the mailbox; will she be too angry to come? Then the party: the boys are waiting impatiently when Amy arrives with her parrot, who repeats after her--"HAAPPY BIRRRTHDAY, PEEETERRR!" In a refreshing switch, the kids are dis-integrated: all but one is black, or rather varying shades of brown. Other apt touches: the lightning that crosses from the flaps to the endpapers, the mailbox as imposing as a Buckingham Palace guard. In toto, a top artist in top form.