Plot

Neri has Kal promise not to leave the island again. Lena uses HELEN to locate another piece of the Synchronium. Mera appears to Neri to again warns her that time is running out.

Concerned by his capture, Neri has Kal promise not to leave the island again. Lena uses H.E.L.E.N. to locate another piece of the Synchronium. Mera appears to Neri to again warn her that time is running out for Neri to finish her quest. The next day, Neri and Kal are on ORCA, but when he is asked to pinpoint the landing area of the Synchronium, Kal says he cannot. Kal then tells Neri he is going back to the island to have a swim and think about the problem but he instead goes to see Dr. Hellegren to tell him about the new piece. Hellegren isn't eager to sent UBRI forces after it, instead preferring to let the kids find it and then take all of the pieces at once.

Lena does her best to pinpoint the location of the Synchronium, but must use more of H.E.L.E.N.'s resources to do so. Unfortunately an earthquake hits at that moment and the Commander uncovers the extra strain placed on H.E.L.E.N. when he is unable to access H.E.L.E.N. during the emergency. As punishment for their actions, Lean, Cass, Brett, and Benny are assigned to clean-up detail - with Morgan as their supervisor.

Neri ventures into the Outback on her own to recover the Synchronium but she succumbs to the intense heat. She is found by a young aboriginal girl who takes her back to her family's campsite. There she is told a story about a water spirit who crashed to Earth creating the water hole before them. Realising what the story means, Neri dives to the bottom of the water hole and finds the piece of the Synchronium.

Finished with their clean-up duty, Cass takes out her frustrations on Morgan. Neri, exhausted from her walk back to the shore and her swim to the island, is met on the island by her friends who help her back to her nest. That night, as Neri sleeps, a spaceship lands on the island - Mera has returned.