Plot: The Secret World of Alex Mack is an American television series that ran on Nickelodeon from October 8, 1994 to January 15, 1998, replacing Clarissa Explains It All on the SNICK line-up. It also aired on YTV in Canada and NHK in Japan, and was a popular staple in the children's weekday line-up for much of the mid-to-late 1990s on the Australian Broadcasting Corporation