<Tr> <Td> </Td> <Td> This episode's plot summary may be too long or excessively detailed . Please help improve it by removing unnecessary details and making it more concise . (June 2016) (Learn how and when to remove this template message) </Td> </Tr> <Tr> <Th> 52 </Th> <Td> 26 </Td> <Td> "The Chosen One" </Td> <Td> Grant Brown </Td> <Td> Mark Shirrefs </Td> <Td> 9 August 2015 (2015 - 08 - 09) </Td> <Td> 29 May 2015 </Td> </Tr> <Tr> <Td_colspan="7"> <Table> <Tr> <Td> </Td> <Td> This episode's plot summary may be too long or excessively detailed . Please help improve it by removing unnecessary details and making it more concise . (June 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> With the full moon approaching, Ondina tries to warn Erik not to activate the merman chamber, but Erik refuses to listen even to her . A now powerless Zac has seemingly given up despite encouragement from Mimmi, Evie, and Cam . Zac later musters up the courage and follows Erik to the chamber to try and stop him . The girls also race to the chamber to stop Erik . Zac fights with Erik for the stone but he shakes him off and finally activates the chamber . The girls attempt to destroy the stone with their moon rings, but it merely absorbs their power . The chamber drains the magic from the moon pool and slowly begins to kill the mermaids except Evie . Horrified by what he's done, Erik tries to deactivate the chamber but is unsuccessful . Evie arrives and helps an injured Zac to his feet . He successfully deactivates the chamber and saves the mermaids but seemingly dies in the process . Desperate to save her brother, Mimmi grabs the stone and places it over Zac's heart . The stone restores Zac's power and revives him . The stone then crumbles, ending the chamber's threat to mermaids for good . The next day, Ondina breaks up with Erik and he leaves the Gold Coast . Sirena reveals she's a mermaid to David . Veridia meets the group at Rita's grotto and praises Zac for his heroic actions . She makes him and Evie honorary members of the pod and gives Evie her own moon ring . The group joyfully swims out to greet the pod as they return to Mako at last . </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> This episode's plot summary may be too long or excessively detailed . Please help improve it by removing unnecessary details and making it more concise . (June 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table>

Does serena tell david she's a mermaid