It is about a girl named Sam who lives on an island with her father (who's an angler) and her cat Bangs and is home alone a lot. She makes a lot of things up, like Bangs can talk, she has a pet kangaroo, and her mother is a mermaid instead of dead. Most of the time, she's just playing but she also sometimes lies to her friend Thomas that these fantasies are true.
One day, Sam's father tells her to "talk real, not moonshine". She doesn't really know what "moonshine" is, but she guesses that it means lies, or "flumadiddle" as she imagines Bangs putting it. Even though she promised her dad not to "talk moonshine", she tells Thomas that her mother and kangaroo are on a rock called Blue Rock, belatedly realising that Blue Rock gets covered by the tide and that's where the story's drama comes in.
Sam, Bangs, and Moonshine provides examples of
- An Aesop: The book's moral is that there's "good moonshine" (fantasies) and "bad moonshine" (outright lies), and it's important to know the difference.
- Catch Your Death Of Cold: Nearly drowning gives Thomas laryngitis.
- Death by Newbery Medal: Subverted. The book has won awards and it seems a bit heavy with Bangs and Thomas getting caught up in the tide, and Sam's father can't find Bangs due to him being "washed away"... but despite all this, Bangs survives.
- Half-Human Hybrid: Discussed. Sam pretends her mother is a mermaid.
- Honesty Aesop: Sam has a habit of making up false stories and is warned that it will get her into trouble. She tells a little boy named Thomas that her mom is a mermaid who lives in a distant cove. Thomas believes her and goes there (followed by Bangs, Sam's cat) and both are lost at sea in a storm. Sam is very remorseful about their loss and learns An Aesop about not lying to people. Thomas and Bangs are eventually recovered alive, but Thomas is ill from his ordeal (specifically with laryngitis).
- Invisible Parents: Thomas's parents aren't seen.
- Meaningful Name: Sam names the gerbil she gives to Thomas "Moonshine" because that was the word her father used for lies, and it was her lies that led to Thomas nearly drowning.
- Missing Mom: Sam's mother is dead.
- Ms. Imagination: Sam is very creative with her games/lies. Case in point, she imagines having a chariot drawn by dragons.
- My God, What Have I Done?: When Sam lies that her mother and kangaroo are at Blue Rock, causing Thomas to go there, then realises that the tide is coming in, she feels incredibly guilty.
- Neologism: Sam comes up with the word "flumadiddle" to describe lies.
- Non Sequitur: When Bangs "reminds" Sam about the tide, she replies, "Pardon me while I go to the moon".
- Talking Animal: Discussed. Bangs can't actually talk, but Sam imagines he can.
- Unnamed Parent: Sam's father is unnamed.
- Vague Age: We don't really know how old anyone is. Sam looks and acts about eight or nine and Thomas looks four (which would explain his naivete) but he's old enough to ride his bike to Sam's house alone.