Jeremy Thatcher is a normal artist-in-the-learning guy, having fun and hanging out-until the love note comes from Mary Lou Hutton saying that she will kiss him after school if it is the last thing she does. Jeremy runs away as fast as he can after school and ends up on a street that he has never seen before, and on it there is a shop called Mr. Elives Magic Shop. There is a strange ball there and Jeremy buys it. Jeremy finds out that it is a dragon egg and he then hatches it. Jeremy names the she-dragon Tiamat. Though Jeremy loves Tiamat, the time rapidly approaches when Tiamat must leave Earth to go to the world where dragons live. There is a new note from Mr. Elives that says that Jeremy must bring Tiamat along with all the eggshell, skin, and teeth that she has shed and broken to the corner of Main and Not Main at 11:30 on Midsummer Night. The time comes for them to part, and the children's librarian(with the help of Mr. Elives) makes a gateway to another world with Tiamat's skin, eggshell, and teeth, and Tiamat leaves Earth.Jeremy is sad, but on Halloween, Tiamat returns in his head, and Jeremy has peace and is happy once again.