Final answer:
Agatha, Chromosa, and Pentagon are not recognized as historical figures or part of a known dog story, and without additional context, it's challenging to provide a summary about them.
Step-by-step explanation:
I'm sorry, but the names Agatha, Chromosa, and Pentagon do not correspond to any widely recognized historical figures, nor do they appear to relate to a specific well-known story about dogs.
It's possible that these could be characters from a fictional story or a local legend that isn't broadly known. Without any additional context or information, it is difficult to provide a summary or any relevant details.
If these are characters from a book you are reading in class or a story being studied, please provide more details so I can give you an accurate and helpful response.