Dejah Thoris Vol. 4 Series by Amy Chu

The untold story of the Red Martian princess! After learning of the legendary Gardens of Mars from her grandfather, Dejah Thoris, Princess of Helium, sets off on a dangerous scientific expedition to save her dying planet. But things don't go the way she planned when she encounters a mysterious Green Martian prisoner... A prequel to Edgar Rice Burroughs' beloved book A Princess of Mars.

Within the ancient city of Thurd, Dejah Thoris finds what she's looking for with the unlikely help of the green Martian. And a long-forgotten secret of Ephysium comes to light…

Water, water, everywhere… The Princess of Mars discovers the hard way what it means to be a Jeddak as she faces an unthinkable situation on the barren planet of Barsoom, death by drowning…

Tardos Mors, Jeddak of Helium sends Dejah Thoris on a scientific mission to chart air currents and atmospheric density tests. But Dekana Lor, Headmistress of the Royal Academy of Helium hints at a second secret mission to the princess. And who is this handsome Red Martian prince and why is he suddenly part of the team?