Quick recap
Opal Koboi fakes a coma, escapes the clinic and leaves a clone in her place. She kills Commander Root in a trap and frames Holly for it. Then she goes after Artemis, who, with his memory wiped, has gone back to being just a thief: he's just stolen the painting The Fairy Thief. Holly, now on the run, saves him, but his memories don't return. The two end up in an abandoned theme park full of trolls and are rescued by Mulch and Butler. Mulch gives Artemis the disk with his memories, and he apologizes to Holly. Together they divert the probe Opal planned to use to expose the fairies to humans. Opal is arrested, Holly is cleared and quits the LEP to open an agency with Mulch.

