I accidentally (almost) did this for a one-shot.

I gave the players a brief scenario summary and three of them choose secret-aligned-with-the-enemy or mercenaries working for the enemy. The last, unwitting player, chose to be a goody two shoes good guy.

Before it really got off the ground, the players were expected to step in and stop some bad guys from beating up a commoner. The 'good guy' did, and all the bad guys and bad players turned on him.

It was a little funny but a big sigh moment when they figured it out.