Clockwork Octopus by Kendra Moreno

Victoria Greene always thought that returning to London would put her life back in some sort of order. The adventure was over, the mission completed, and she assumed she could continue her work with machines in peace, but Vic should have known that such a thing was not possible. Instead, she suddenly finds herself dealing with judgmental Elite, the corrupt High Council, and the certainty that London has deeper secrets than she ever knew. When the Queen of England sends Vic and her men on yet another task of the highest importance, Vic is relieved, if only to escape the city that feels less like home than an airship.
But Vic is not the only one racing around the world. The High Council is on their tail, and they have no qualms about doing anything it takes to win.
Now, the Lost City of Kásskara beckons, and with Bram, Emory, Jules, and Jed by her side, Vic must find the sunken world fast. There are too many perplexities surrounding the disappearance of Kásskara and no one wants to speak its name.
Some cities should never be discovered. Some machines should never be created. Some secrets were meant to die in the past.
And sometimes, it is better to follow the compass than the clock. . .