This sounds like fun!

I think there’s a fair amount of information that’s not needed here to understand what the story is about. There’s a lot of detail but not that much that helps the reader to visualise the story and that’s really important. The siblings “learn of the possible existence”. Learning something isn’t particularly visual and it’s only a possible existence. They need to find something that damn near proves it, at least enough to start their quest. Think of The Goonies – they find the treasure map and translate the text – yes they learn something, but the logline would be “when they find a treasure map and decipher the location of the loot”. ?It’s all visual, exciting, and gets the team involved. It’s not 100% confirmation but it’s enough to get them excited and starts them down the road to the treasure.

“piece together the truth” – how is this represented on screen? Visually, what’s happening?

“Powerful opposing forces” – what are these? Again, think visually. The reader has to either make assumptions or speculate as to what these are and that’s one of the last things you want a reader of your logline to do. If the assumptions or speculations are wrong, and based on them the reader chooses not to read your script, that would suck! Be more specific – is it a company? A group of dragon killers? A medieval wizard who banished all the dragons and is resurrected once the siblings put the puzzle together (in the inciting incident).

“see sawing battle of wits, steel, meerkats, and witty repartee.” – In a family film about rival forces trying to each find something first, personally, I think most of this is a given. Obviously the meerkats is the exception. I don’t need this information as this is what I’d expect – what I do need though is (as dpg pointed out) to know what the prize is? What’s the goal? What are the stakes? And again, think visually, make it a tangible goal that the reader can understand. Ideally, this is “to find the dragon and…” maybe save it from the opposing forces or gain control of the dragon to stop the bad guys using it for death and destruction.

Hope this helps… keep going with this! It sounds great!

Sounds good!

I’d consider removing “before they are killed”. I’m not sure it’s necessary as the danger is implied enough. Also, it confuses me slightly… vigilantes take the law into their own hands without ?legal authority – they want justice. Yes, things may get out of hand – mob mentality – but would they kill an innocent 5 year old girl? Remove this line and you remove all issues and I don’t think the logline is worse off. Others may disagree.

Can we make him a gang-leader not just a member? Make the target on his back bigger? There’d be a more obvious “why this guy” and it would explain why the vigilantes were pursuing them. ?In this vein, I don’t think that you need him to be venturing through enemy territory. Can’t he just avoid enemy territory? It sounds a bit convenient? If the vigilantes are chasing him, he could just be anywhere. He still needs to get to sanctuary and it makes everywhere unsafe for him. They need to be doing more than just raiding… particularly if you’re suggesting their lives are at stake.

My only other issue is that you have to get the audience to sympathise with a gang-member/leader. It can’t just be because he has his daughter with him. Can he be an ex-gang leader? Seen the error of his ways?

Set in the near future: When vigilantes take to the streets and attack gang members, a repentant ex-gang leader must escape across the city to sanctuary with his 5 year old daughter.?