Moose's mom is staying home from piano lessons and hiding in her room, upset. At dinner, Natalie can tell that something is wrong; she starts rocking back and forth. Dad and Moose tell her that Mom is mad—but emphasize that she isn't mad at Natalie.
Moose tells his friends about his crazy idea involving Al Capone. Annie tells him that he's been spending too much time with Piper, if he's getting these sorts of ideas, which is probably fair.
Moose comes to Piper with his plan: He's going to write a letter to Al Capone. He figures that he can send it through Piper, since Piper's mom censors the mail. Piper tells him it won't work, though, because she's already tried to send letters of her own and never heard back.
Moose is determined, though, and the next day, he uses her typewriter to write his letter.
He puts the letter in an envelope and gives it to Piper to put in the mail. Piper asks him if he'll have to go back to Santa Monica if this plan doesn't work. When Moose asks her why she cares, she denies having any interest in the subject at all.