The Trident is active and dangerous, and the mermaids must take it from Zac. Knowing this, Zac searches for the perfect hiding place and decides on an old warehouse.
The Trident is every bit as powerful as Zac imagined. Only, he can't get it to work! Zac wonders if the Trident needs to be activated by moonlight and breaks into Rita's secret Grotto.
Will pushes himself too far when Zane challenges him to prove his skills as a free-diver. The girls discover a unique crystal in the rock from the Moon Pool.
Kim attempts to derail Don and Samantha's wedding. Lewis receives an opportunity to study in America. Cleo realises she's got to let Lewis live his own life and let him go overseas.
Rikki receives counterfeit money at the cafe and is held captive by criminals on a boat. Bella and Cleo are forced to reveal the trio's secret to Will so they can rescue Rikki together.
Bella helps Will with his free-diving training but when she realises he's more interested in her as a mermaid than a girl, she's hurt.
Abigail's best efforts to balance her ballet commitments with the fringe musical splinter when a leaked staff email discounts her chances in the Prix de Fonteyn and her over-supportive mother Anthea unexpectedly arrives at the Academy.
Tara hunts for a new crush while the director of a fringe musical tries to convince Abigail to be the star of his show and Grace goes to increasing lengths to get Zach's attention.
Daniel has knocked the wall through, determined to investigate these amazing tunnels which lead directly into the den. Emma is convinced their time at the house is over. Their secret is out. But Maddy and Rhydian try to persuade her that Liam may not know what he's seen or where he was. They will go into school, having phoned Tom and Shannon to find out what they can.
Liam returns to school after his ep 10 trauma. Maddy and Rhydian aren't in registration. It's the day of the full moon and Tom surmises they are out having fun. But what they are actually doing is fleeing for their lives from Alric who is out for revenge. Maddy tricks Alric into using Eolas under the electric power lines and they escape. In school, oral exams are taking place in the hall.
The day before school Parents' Evening, Maddy, Tom, Shannon and Rhydian are helping Jana clean her caravan. Rhydian's Mother, Ceri, shows up. But it's not just Rhydian she has come to see. She tells Jana that her Father Alric has been deposed by the pack, making Jana the new Alpha. If Jana doesn't assume her destiny as heir, the pack will destroy itself as betas fight for control.
The class are Camping overnight in Aern Hollow before the orienteering task the next day. Liam has his ancestor's journal with him outlining how he found and tracked the werewolf he shot (ep 3). In their respective tents, Maddy, Jana and Rhydian use their wolfblood hearing to listen in, telling Tom and Shannon what they hear.
Alex is too sad about Marcus having dumped her and effectively split up the band Smash to do her school - or domestic work. Even ever-respectful Kuru can't deny she lacks commitment, especially as the princess. She now declares herself ready to accept the throne.
BRANDON is furious with everyone – and especially ZOEY – for lying to him. How could they keep a secret like this from him?
Nicu and Lars find themselves at Dracula's castle, where he wakes up the remaining Upiry. A bad deal is on the table for Alisa to defeat Dracula. Ivy's visions show her new insights as she learns time is running out for Alisa and all will be lost if they don't hurry to get to the Knot in time. But will Alisa and the others be strong enough to face Dracula and his army?
A full moon. A Halloween party at the café. The perfect chance for Zac to seize the Trident. The mermaids keep a close watch on Zac at the party, but with Cam's help, he evades them.
Zac finds a Moon Ring on the ocean floor and when he gives the ring to Evie, the mermaids know it's no ordinary ring. They have to get it back!
While showing off his brand new smart phone, Cam takes video footage of Zac swimming as a merman.
Bella's warned to back off from Will as he's on the trail of the girls' mermaid secrets. She gets too close to him and he finally discovers she's a mermaid.
Cleo defies Lewis' advice and experiments with the magic Moon Pool water. Using her powers, Rikki accidentally gets the water into Cleo's aquarium.