Arthur and his classmates are preparing for a field trip to some caves in Palisades Park after making replicas of caves for homework. Mr. Ratburn discusses mostly bats, and other creatures that live in there. He reminds them of the replicas, and that they're due tomorrow.
During class, Francine teases Arthur of being scared of going inside a cave, which annoys him. Mr. Ratburn explains what “spelunking” is, to which most of the students are looking forward to and he claims the caves will seem less frightening the more they study them. He then reminds them of their homework before class ends.
Upon learning this from him at home, D.W. tries to make Arthur admit to being scared going into the caves, even going so far by trying to pull scary tricks on him, though Arthur isn't actually moved by them at all, much to D.W.'s anger.
Trying to make him feel better, his dad tells them a story about the basement he was afraid to go into as a child. But to solve this, he would whistle a comforting tune a little bit in order to help him conquer this fear.
Later, D.W. keeps trying to scare Arthur, but it's no use, as he just won't budge. He turns the tables by taunting her before going to bed, leaving D.W. really upset.
After a good dream of whistling a familiar tune while being trapped inside a cave, Arthur is less hesitant and seems less frightened. In class, Mr. Ratburn overlooks the replicas one by one.
Brain then shows him and the others how much work he put into his own replica when it lights up. Muffy then asks if bats give people rabies, but both Brain and Mr. Ratburn deny this. Mr. Ratburn then scolds Francine and tells her it's perfectly natural to be frightened at first.
When the day of the field trip comes, he's noticeably not the only frightened student or member there. But Arthur is determined to get through this to prove he is not scared, and they keep exploring.
They spot a swarm of bats sleeping, and Mr. Ratburn and Francine start to panic after some time, which ends up scaring the bats after Muffy points them out. Binky takes pictures of Mr. Ratburn and Francine while they're panicking.
After some time, and some reassurance from Brain, Francine and Mr. Ratburn slowly calm down, while Arthur and the other kids (as well as their tour guide) remain calm.
In order to help the tour guide in getting Mr. Ratburn and Francine out of the cave calmly, Arthur (acting on his father's advice) suggests whistling a familiar tune, to which everyone does so.
After Arthur and his classmates get out of the cave calmly, Mr. Ratburn and Francine apologizes to everyone for their panic attacks and thanks the guide for helping him and Francine out of the cave, as well as thanking Arthur for his helpful whistling tip.
Binky proves this wrong by having taken two pictures of Francine and Mr. Ratburn being scared while seeing the bats.
The episode finishes with Francine dreaming that she has grown a pelican's bill after Binky called her a bigmouth.