Return to Fortuna

"Desperate to know whether their real parents are still alive, Polly, Lisa and Lydia make a brave return to the troubled underwater city of Fortuna, this time taking their friends Matt and Kelly, with them. The rebels of the Southern Quarter are under constant siege from the dreaded Polizia but are preparing to fight back. With the help of Matt and the girls, they plot to overthrow the tyrannical Imperial Governor and his supporters. But while Polly, Lisa and Kelly have to use all their wits to try to avoid capture, Matt and Lydia enter a terrifying place from which no one has ever returned…" --Publisher.