I finally found a copy!!

In the first chapter, Opal Koboi, the evil pixie from the 2nd book was in an expensive fairy/magical creature hospital. She supposedly was in a coma, but at first, the hospital was suspicious of her and were worried that she might be faking the coma, a skill found in some pixies. The hospital started out with a dozen guards watching her in her cell, (It is a hospital with some rooms that are cells) a bunch of cameras around her, and 4 DNA scans a day. Once the coma lasted for almost a year, and with the mind wave detector thingies picking up only a few dream spikes now and then, though, the hospital people were pretty sure it was a real coma. The amount of guards dropped to one, and there was only one DNA scan a day. After almost 2 years, Opal Koboi still seemed to be in a coma. But it turned out that she really had been faking it, and her mind was almost disconnected to her body, in a way, but nobody knew but her and the two janitors, who were also pixies and were working for Opal Koboi. They were keeping it a secret, though. They made a clone of Opal Koboi that had her DNA, and helped her get out, replacing her with the clone.

Meanwhile, Artemis, who is still mind wiped, is after a painting called The Fairy Thief. He and Butler broke into a bank by tricking the person there, and they have just gotten the painting. It was funny, because Artemis was discised as an antisocial, sarcastic, teenager, and he did a really good, hilarious impression. I think that when they look closely at the stolen painting, it will trigger their lost memories of the fairies.