Anthony Adverse was a historical novel (1933) by Hervey Allen (1889-1949), made into a major motion picture in 1936.
"I never read it but used to see it on the cheap paperback shelves in the 40s and 50s. Any precocious kid hanging around the local public library, once admitted to the adult section, might have stumbled across it."
"I read the damn thing as a teenager. It was probably the biggest bestseller in the U.S. before Gone With the Wind. The novel became a rather minor family joke when my grandmother, who was reading it when it first came out, once announced to my mother and her younger sister (my aunt) that she was getting tired, so she thought she'd go upstairs to bed with Anthony Adverse. My mother (rest her soul) with her propensity for endless yakkitying probably at one time or another related that story to John."
Crapple: a claw. There is nothing significant about the name except Bellairs having fun coming up with bizarre-sounding words.