As Nazi forces ready a counterattack after the first wave of the Warsaw Uprising, a scrappy Polish courier must cross the occupied city with three boy-scouts turned soldiers to recruit their battalion for a dangerous mission — liberate a concentration camp before the SS can kill its inmates.

BTW: assuming that in real space and time, it was a just a troop of Polish boys, I don't think it mandatory to designate a main character in the logline. It could be an ensemble story. (Unless there was an alpha character, a prime mover who was responsible for galvanizing the group and lead the liberation attempt.)

A high concept story sells itself without needing to slavishly adhere to all the usual rules for constructing a logline.

Wanted to add also that I agree that the liberation of a concentration camp would be far higher ambition than aiding a ghetto uprising. Higher stakes and originality do make this a high concept.

Good point about the notion of a single plot this also strongly relates to Aristotle's argument for a unity of action of a plot in the Poetics.

That's why I didn't specify a concentration camp rather only mentioned the Warsaw uprising in my suggestion.

Wanted to add also that I agree that the liberation of a concentration camp would be far higher ambition than aiding a ghetto uprising. Higher stakes and originality do make this a high concept.