A mermaid, Patty thinks as she watches Allison’s blond hair sink underwater and rise up again, along with a luminescent tail in a color that reminds Patty of dragon scales.

But what kind of mermaid has sharp teeth like glass shards when she smiles and sinks them into her husband’s neck?

I’m going to kill Kevin, Allison had said; this is not the way she expected her to follow through.