<Tr> <Td_colspan="7"> When David delivers a seafood order to Rita's house, Evie, who is still suspicious of the girls, tags along hoping to find out more about them . Meanwhile, Rita's cat, Poseidon, becomes magically enchanted after stepping through a puddle of spilled potion . After encountering Evie, who was snooping around the house, Poseidon transforms into an exact duplicate of Evie but retains the mind and instinct of a cat . David mistakes feline Evie for the real Evie and takes her back to the cafe . Later, feline Evie goes to the beach with Carly where Cam notices her odd behaviour and calls Zac for help . While searching for Poseidon, the girls run into Zac and "Evie" at the beach and eventually realise what has happened . Lyla helps Zac keep the real Evie and Poseidon apart while Nixie and Sirena work on a way to restore Poseidon to cat form . </Td> </Tr> <Tr> <Th> 23 </Th> <Td> 23 </Td> <Td> "Zac's Choice" </Td> <Td> Grant Brown </Td> <Td> Chris Roache </Td> <Td> 22 December 2013 (2013 - 12 - 22) </Td> <Td> 15 September 2013 </Td> </Tr> <Tr> <Td_colspan="7"> Rita begins giving the girls lessons on how to use the Moon Rings . Meanwhile, Zac is searching the reef for the trident and recruits Cam to help him find it . When Lyla goes to check on the trident, she sees Zac retrieving it from its hiding place . As Lyla tries to take the trident from Zac, a bolt of lightning jumps out from it and strikes her, knocking her unconscious . Horrified by what he's done, Zac picks up Lyla and brings her to Rita's grotto, leaving the trident for Cam to bring back to shore . Sirena, Nixie, and Rita attempt to use their Moon Rings to heal Lyla, but this fails when the rings run out of magic . Rita realises that their only hope of saving Lyla rests with using the trident to recharge the Moon Rings . Zac retrieves the trident and brings it to them despite Cam's protests . He recharges the Moon Rings, which the mermaids then use to heal Lyla . After recovering, Lyla tells Zac about the trident's ability to destroy the Moon Pool . Zac finally realises how dangerous the trident truly is and returns it to its resting place on Mako Island, ending his feud with the mermaids . However, Nixie is unsure if Zac can be trusted to let it remain there . </Td> </Tr> <Tr> <Th> 24 </Th> <Td> 24 </Td> <Td> "Trust" </Td> <Td> Grant Brown </Td> <Td> Anthony Morris </Td> <Td> 29 December 2013 (2013 - 12 - 29) </Td> <Td> 15 September 2013 </Td> </Tr>

When does zach find out mimmi is his sister