Secrets of a Summer Spy — Janice Jones

Usually, Veronica (Ronnie to her friends) can't wait for summer vacations on Harbor Island, where she reunites with her friends Amy and Jimmy, and the three of them become the "Clamdiggers."

But this summer is different. Instead of having their usual adventures Ronnie's personal favorite is "spying" -- they seem to be going in opposite directions. All Amy can think about
is Jimmy -- or Jim as she calls him now -- and the feelings
seem mutual.

So Ronnie's out in the cold. But she'll show them. She begins spying on strange Mrs. Peet, the eccentric "catlady" who lives in a nearby cottage, never dreaming that she's about to begin the adventure of her life....