With Tide and Tempest (Secrets of Itlantis) (Volume 3)

Free or not, life beneath the sea in the republic of Itlantis is less idyllic than Aemi might have imagined when she'd been just a surfacer slave. She's been accused of spying for the enemy thanks to her connections with the traitorous Nautilus family, not to mention her own tangled and mysterious family history. Her mother has arrived, and is determined to take over her life. Oh, and someone is trying to kill her. Again. When Aemi receives word that her best friend might still be alive in a village on the surface, she and a crew of friends set out to find him, regardless of the danger from Nautilus's men patrolling the open sea and the mysterious threats on her life. But the sea is not the only thing that holds secrets.