A hypnotist's show turns out to be way more than Zack bargains for when he is pulled out of the audience, put into a trance, and his body is "taken over" by the spirit of someone from the past. And that's only the beginning, because the stubborn spirit won't go away when the show's over! It's hard enough having just one self to worry about. What will Zack do with two?

The Zack Files #12.

When Zack accidentally drinks the invisible ink that is one of Spencer's experiments, he worries about missing his only chance to get his picture in the paper, if the new flavor he and Spencer invented wins the local Len and Larry's Ice Cream contest.