Persuaded by the word "treating" to dress up as a princess for Halloween, Mercy the pig's trick-or-treat outing has some very unexpected results.

After Mercy the pig snuggles to sleep with the Watsons, all three awaken with the bed teetering on the edge of a big hole in the floor.

Frank Endicott is a worrier. He worries about lions, submarines, black holes, leprosy, and armadillos. He lists his worries alphabetically in a notebook and suffers vivid nightmares that even a certain neighborhood pig can't dispatch. When he accompanies Eugenia Lincoln on an errand to duplicate a key at her favorite dark and dusty thrift shop, Frank earns fresh cause for alarm. Odd Buddy Lamp, the shop's proprietor, has sent them home with the original...

Stella Endicott loves her teacher, Miss Liliana, and she is thrilled when the class is assigned to write a poem. Stella crafts a beautiful poem about Mercy Watson, the pig who lives next door -- a poem complete with a metaphor and full of curiosity and courage. But Horace Broom, Stella's irritating classmate, insists that Stella's poem is full of lies and that pigs do not live in houses. And when Stella and Horace get into a shouting match in the...

When Mr. and Mrs. Watson and their pig Mercy take in a movie at the Bijou Drive-In, mayhem ensues after Mercy smells the enticing scent of hot buttered popcorn.