H2O: Just Add Water - Season 2 - Eps 21: And Then There Were Four
Charlotte's stubborn nature and thirst for knowledge leads her to Max, who confirms her suspicions and leads her to the Moon Pool. Lewis meanwhile is having trouble trying to keep their relationship together.
About H2O: Just Add Water

Title: H2O: Just Add Water
First Air Date: 2006-07-07
Last Air Date: 2010-04-16
Status: Ended
Rating: 7.8/10 (from 661 votes)
Language: EN
Seasons: 3
Total Episodes: 78
Network: Network Ten
Genres: Drama, Family, Sci-Fi & Fantasy
Production Companies: Pacific Film and Television Commission, Jonathan M. Shiff Productions, Network Ten, ZDF
Synopsis
H2O: Just Add Water revolves around three teenage girls facing everyday teen problems with an added twist: they cope with the burden of growing a giant fin and transforming into mermaids whenever they come in contact with water.
Cast

Phoebe Tonkin
Cleo Sertori

Cariba Heine
Rikki Chadwick

Indiana Evans
Isabel "Bella" Hartley

Luke Mitchell
Will Benjamin

Burgess Abernethy
Zane Bennett