Baby Kate and the Imaginary Mystery When Nadine misses an appointment for tea with Vicita's imaginary friend, Tweenie, Baby Kate and Pal grow concerned. They launch an investigation, worried that she may have been kidnapped by the Tibbles. Along the way, Francine's cat Nemo is pulled into the investigation. Strangers on a Train Sue Ellen is excited at the prospect of riding an "old-fashioned" train, but discovers that the train seems to be just "old" instead. It's really run down and with no other kids riding, she's worried the trip isn't going to be any fun. Then, the discovery of a mysterious diary looks to brighten the prospects for adventure on the trip.