Ex-convict Eddie (Henry Fonda) and his new wife Joan (Sylvia Sidney), a public defender's secretary, are honeymooning at a hotel somewhere in a rural area outside a big city. They are outside at night. We see a little artificial pond and hear Pacific Treefrogs calling (but when we see several frogs sitting on lily pads on the pond which are supposed to be the frogs we hear calling, we see American Bullfrogs.)
Then Eddie and Joan have what must be the strangest honeymoon conversation about frogs ever heard in a movie. It's a conversation that foreshadows the rest of the film in a very un-subtle way.
Eddie: "Listen, they sound just like crooners, don't they?"
Joan: "Some crooners."
Eddie: "When I was a kid, we used to catch them in the sewer drains. Some of the kids would pull off their legs and fry 'em in bonfires. Used to make me sick. I got my first rap protecting a frog's life. It's the truth! I caught a kid doing that to a frog once. I beat him up. His mother sent me to a reform school."
They sit on a bench next to the pond, sneaking up to it so they don't scare the frogs away, and we see two bullfrogs sitting next to each other.
Eddie: "You know something about frogs? If one dies, the other dies.
Joan: "That's funny. Why?"
Eddie: "I don't know, except they just can't live without each other."
Joan: "Like Romeo and Juliet."
Eddie: "No kidding, that's how they are."
Joan: "How do you know so much about frogs?"
Eddie: "I've always known that. I though everybody did."
We see Eddie and Joan's reflection in the pond. Then a frog jumps into the water, distorting the reflection.
Joan: "I guess they see something in each other that noone else can see."
You've probably figured out by now that things will not go well for Joan and Eddie.