Grumpy Rat’s mood changes completely when he finds an unsigned letter in his mailbox one day that reads: “This letter is from someone who really admires you. I think you are very special, and I just want you to know how lucky I feel to have such a true and dear friend as you.” Rat is certain that the letter was written by his neighbor, Mouse, and he rushes over to Mouse’s house to thank him. Mouse, however, has been busy repairing his roof, damaged by a storm, and hasn’t had time to write. While Rat helps with the roof, he and Mouse ponder who the letter-writer might have been. It turns out that each friend Rat suspects has been dealing with a challenge of his or her own and welcomes Rat’s help when he arrives. When Rat gets to Bat’s house, he finds Bat in a serious blue funk. Rat’s solution? A friendly letter, of course! Anthony France underscores many ways friends can help one another in a lively picture book that has a gentle air of mystery as the source of Rat’s original letter is implied but never revealed. (Ages 3–7)