Complex sentence: Jerbal Argon is the owner of a health clinic in, though he first appeared in Artemis Fowl, in which he watches the video of Artemis to determine if he is lying when he says he can escape the time field.
Split into simpler sentences: Jerbal Argon is the owner of a health clinic in, though he first appeared in Artemis Fowl. In his first appearance, he watches a video of Artemis to determine if the boy is lying when he says he can escape the time field.