On the verge of capture, Vera, a peevish teenage Jew, flees the Nazi invasion of her Romanian village and crosses paths with a British secret service agent who reluctantly mentors her after she learns of her family’s murder. When her mentor is exposed as a double agent, she launches a vicious global vendetta to bring Nazi war criminals to justice before they can disappear into post-WWII hiding.

You shouldn't need to explain the need for a mentor in a logline, as mentors are archetypes often used in many genres. To that matter the presence of a mentor may work well in the story, but their mention in the logline is not necessary either.

As Nir Shelter said.? The cause-and-effect relationship?doesn't seem?strong and clear enough.? Make it personal. She may?dedicate her life to finding and?bringing to justice former Nazis, but?she's?after one Nazi in particular, the one who was responsible for the death of her family.

As Nir Shelter said.? The cause-and-effect relationship?doesn't seem?strong and clear enough.? Make it personal. She may?dedicate her life to finding and?bringing to justice former Nazis, but?she's?after one Nazi in particular, the one who was responsible for the death of her family.