This covers most of the bases:
Your breath fogs in the night air as you stop to rest. You stand on a mountainside staircase, not fifty feet from the grand balcony that admits visitors to the palace home of the dwarf prince Rabi Guratf. Through no small effort of climbing, conniving, and collusion, you have passed several guard stations to reach this final obstacle.
Somewhere within the palace, Prince Rabi prepares for his momentous speech to-morrow. After months of preparation, his armies stand ready, and he will declare open war on the neighboring kingdoms of humen and mountain dwarves. He has forbidden all visitors on this eve of war.
Some of you are friends of the prince. He has listened closer to his war council than to you, and turned a deaf ear to peace. You are here to make a final plea to avoid the bloodshed.
Some of you do not know the prince, but you know that war is not the answer. You are here to help the prince’s friends reach him, for your own reasons.
Your planning for this adventure yielded three final paths: scaling the palace wall, entering through the dungeon, or walking in the front door. Any route would be difficult for a full-size party, but you’ll be able to manage if you split into smaller groups. You’ve also decided that the overnight guard watch is of a manageable size (about fourteen guards plus a sergeant-of-the-guard), but if an alarm should be raised, you would be quickly overrun unless you can hide long enough for the reinforcements to go back to bed.
Choose a hero, choose a party, and prepare to make history.