Vicky of Venus

In the action-packed companion series to Molly of Mars, the planet Venus, mystery, aliens, and new friends await Vicky Valentine. She takes charge of her family's Vacationland theme park in the floating colony of Venusville. But when trouble strikes her first big assignment, she must lead and find the villains jeopardizing everything.

2 books in 1:
Vicky's Venusville Vacationland
Vicky's Vile Victory

For ages 10+ (like Harry Potter level)

Try Vicky's other adventures in the Molly of Mars series:
Molly of Mars and the Alien Syndicate
Molly of Mars and the Alien Nebula
Molly of Mars and her Alien Sister
Molly of Mars and the Alien Creatures

Molly of Mars in Pirra's World: Alien Spacegates
Molly of Mars in Pirra's World: Alien Cages
Molly of Mars in Pirra's World: Alien Revolt

Or try my PG-13 series, Lunara.