The caller will tell you when that's the case. Hey My favourite figure. Wonderful flowing motion. Sixteen beats for a full hey. Several variations in starting formation, but typically one couple facing another across the set, ladies on the gents' right.
Ladies start first, followed almost immediately by the gents.
From where you are, walk across to the other side of the set, make a nice loop when you get there and walk back to the side where you started. You end up in exactly the same spot you started from. The fun part is that everybody does this at the same time, crossing paths in a weaving motion. All couples face down the hall, away from the music. Twos step apart from each other and ones step in-between the twos.