Seven against Mars

Trapped in the Warsaw ghetto in 1942, teenager Rachel Zilber escapes the horror by writing about the adventures of Zap-Gun Jack and Princess Anya of Mars. When her parents are captured by the Nazis, Rachel's transported into her make-believe world, but the danger is far from over. Together with Katie, a girl from the future, Rachel joins Jack and a rag-tag band of misfits to fight the evil Lord Ares III of Mars and restore Princess Anya to her rightful place on the Martian throne.