The story of Blue's Clues is quite simple to explain. In each episode, Blue leaves clues for Joe so that he can figure out what kind of things Blue wants to do. When he sees a clue, the object (or person) will have Blue's pawprint on it, which looks like this:
When the clue is spotted, it is recorded by Joe in his notebook and kept in there over the course of the search.
There are three different clues to find. Along the way, Blue and Joe meet up with many different characters and assist them in various activities.
When all three clues are found, it's time to race to the "thinking chair" to piece together the puzzle, using the three clues.
With a little thought, the puzzle is solved. Then the gang can do the activity that Blue wants to do together! Simple, huh?