A new character with a Mark was introduced in this episode. Anna Graham who happens to be a boy has the Mark of Da Vinci. It quite weird though because Da Vinci sounds and acts like a girl. But that is of little relevance to the story. It should be Obvious that Da Vinci is an artist. He sounds most of his time in the art room painting.
The Puzzle they had to solve was quite interesting. It involved paintings and having to line them up according to their patterns on the frame. I will let watch the show to figure out the rest. No point in spoiling it. All I can is that without Da Vinci their Einstein would have never figured out. Then again he probably would have tried his idea out anyway. It would seem that a nice puzzle solving gang is being assembled with Einstein as it’s leader. So people with marks include Einstein, Galileo, Edison, and Da Vinci. By the intro it does not seem like their will be anymore.