This is a creative writing project. I need a children's adventure story with 7 characters - 5 children and 2 dogs. The names of these children are Crispy, Ruby, Jack, Goldie and Hummus. The 2 dogs are called Ritzy and Poppy. Crispy will be the leader and have a personality of someone level-headed with integrity and he is protective of his friends, but always serious. Ruby will be intelligent and studious with all the facts, but awkward at times. Jack is playful and energetic and into sports. Goldie is eccentric and absentminded but really good at heart. Hummus is a little chubby and naive, with a weakness for food. Ritzy is gentle and intelligent. Poppy is small, hyperactive and ditzy and competes with Hummus for food.
The bunch of them are on MYSTERY ADVENTURES together to explore the world by a magical train called the Brain Train. There are no limits in terms of the physics of their world, they can magically enlarge or shrink to microscopic levels to explore microscopic worlds, while their train can fly or go underwater (think Magic School Bus type of adventures). But please NO fictional animals or creatures.
Please come up with an overarching mystery plot such as that coming from the Usborne Puzzle Adventure Book series (example solving a crime, looting of treasure from an ancient city, escaping from kidnappers, solving a kidnapping, etc) that takes them through the mountains, valleys, rivers, oceans, deserts tropical and temperate rainforests, in the skies, land and seas while interacting with animals, insects, plants, fish and sea creatures of all sorts.
The themes, language and complexity of story should be targeted for ages 6-12. So please no adult themes, romance or violence. There is no need for detailed descriptions of environment as this story will be paired with illustrations. There is no need for character development. No minimum or maximum limit to the story as long as the plot is complete.