An wanderer and a space princess must stop an evil emperor from having their town by ecologists in order to protect the environment.

An wanderer and a space princess must stop an evil emperor from having their town by ecologists.
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I believe the purpose of a logline isn’t just to convey a story in a concise manner, but also to see if the writer can write one single compelling sentence.

After all, a script or book is basically a series of compelling sentences, that when strung together, tell an equally compelling story.

Therefore, before anything else, I would first make sure that your logline is the best sentence you can possibly write.

Anyway, just some thoughts, Hope this helped!

(BTW, I can’t tell from logline whether this is for the Edger Rice Burroughs story, ‘Princess of Mars’ or your own original story with the same name)