Dragonbreath itself has Danny whipping up a very poor paper on the ocean while on the bus, and deciding to research by visiting his Cousin Edward. A sea serpent. He and Wendell take the bus to the Saragossa Sea. (Wendell is a bit weirded out; Danny assures him it's a good bus system.) And Cousin Edward gives them breath mints and takes them into the sea. A sunken ship, squid, whales, puffer fish on a coral reef, and more things.
Attack of the Ninja Frogs has Suki, a salamander, arriving as an exchange student. She has a little problem: ninja frogs keep trying to kidnap her. Fortunately, only when she's alone; Danny and Wendell foil one just by showing up. Danny asks his mother for help. She suggests he consult his great-grandfather, who lives in Japan. They take the bus. Wendell is blase about it; Suki is a bit weirded out. Fortunately his great-grandfather has good advice. The results involve a crane, a chrysanthemum on a mailbox, a volcano, Suki's desire to be vet, and more.
Curse of the Were-wiener: a bright red hot dog bites Wendell at the school cafeteria. The next day he and many other students are itching furiously and sprouting hair. With a little distraction, Danny finds the original package -- they come from Transylvania. They do not take the bus. Calling the number on the package gets some info, but they still need to deal with it in a tale involving the ancient hot dog/potato salad enmity, talking to rats, a food fight, and more.
Lair of the Bat Monster: Wendell and Danny find a bat trapped in the pool filter and liberate it; it doesn't fly off. They bring it home to his mother, who consults Danny's cousin Steve, a bat expert. They take the bus to Mexico. Steve pronounces the bat just tired and hungry and need of a rest. Then he shows them a lot of bats. Once they get out into the jungle, it involves Aztec worship and giant bats.
No Such Thing as Ghosts: It's Halloween. Once attired, they set out, and Danny's father picked up a girl crested lizard Christiana to go with them. (On one hand, a girl; on the other, she once brought a sheep brain to school.) They go trick-or-treating, they meet up with the bully Big Eddie, they end up going, on his dare, to the abandoned house. The door opens. And then it closes behind them. It involves a bull-roarer, a rat who really can lead them somewhere, Wendell's having read ghost stories, a picture of flowers or maybe a clown, and more.
Revenge of the Horned Bunnies: They are off to Camp Jackalope -- Danny, Wendell, Christiana, and alas, Danny's annoying young cousin Spencer. Following Spencer when he sneaks out of camp reveals that jackalopes are, after all, real. Except that most have vanished from the area. The tale involves a section of the camp where campers are no longer allowed, lanyards, a fire alarm installed after Danny's last summer there, and more
When Fairies Go Bad: Not the kind that little girls dress up as. When a fairy circle springs up on the lawn, and Danny's mother picks one to have it while researching the type, she is kidnapped by fairy music the next day. Wendell and Christiana are willing to help, and they consult Danny's great-grandfather who has been complaining of their stealing spoons. Then it's the bus to Faerie. It involves a rhyming curse, tears, a crossroad, smudging a piece of paper, gratitude, and more.
Nightmare of the Iguana: The title iguana is indeed Wendell. He's so desperate that he calls Danny's great-grandfather even at the cost of being called Wanda again. Armed with the knowledge, he gets Danny to watch him at night and see what the problem is. Then they take the bus to the great-grandfather's, and discover Suki's there. (Danny's great-grandfather had given her a bus pass, which lets her reach the mythological bus stops.) So all together, they deal with it. It involves going to a hot spring for an ally, finding the card catalog in a mental library, a long hallway of locked doors, jumping off a cliff, and more
The Case of the Toxic Mutants: Danny's mother sends him off to see his grandfather (on the other side of the family). Wendell and Christiana tag along, and they find some thief has stolen his dentures. Investigating the crime brings them through considering taming butterflies, an old hospital, cookies, Danny's ability to appraise treasure, pawprints that are the right shape and wrong size, and more.
Knight-napped!: Danny's annoying cousin Spencer sends him a message by pigeon: knights have kidnapped him. Christiana is greatly distressed to learn the kidnappers are cousins of hers; she doesn't even object when the bus takes them to Austria and the castle. The rescue involves moats and fake fights, and Christiana being a proper knight, endangered species, and more.