In [year], after a wealthy woman is enslaved in Emperor Nero's court, she must go break out of her demure upbringing and bring down a corrupt system.

I'm not sure if this suggestion is much better, but I would start with the time period and delete out the father's storyline. My big question is what does she do? "Discovering who you are?" This needs to be specific. I put in what I thought it might be, but what specifically must she discover? If it's just inner strength then focus on the stakes and the obstacle: she must overcome the entire court to save her sister before she suffers the same fate. something like that. Cheers!

Thanks Noel. Only just seen this suggestion. It's a good one!

An interesting! Noel’s logline is better too,