Always pass right shoulders.

1 and 5 change with 4 and 8 on two steps:
2 4 6 8    2 1 6 5
    becomes
1 3 5 7     4 3 8 7

2 and 3 change with 6 and 7 on two steps:
2 1 6 5     3 1 7 5
    becomes
4 3 8 7    4 2 8 6

Everybody two steps on the spot, and two steps across.
4 2 8 6
3 1 7 5
Repeat above with 3 and 7 changing with 2 and 6 back to original place
4 3 8 7     1 3 5 7     2 4 6 8
             –›             –›
2 1 6 5     2 4 6 8     1 3 5 7

Middles dance out between ends, 3 & 4 between 1 & 2, and 5 & 6 between 7 & 8 (4 & 5 go first),
and dance most of a figure of 8 around the end two, taking 12 steps and finishing in a line with the ends.

So

2 4 6 8            becomes            4 6
1 3 5 7                                      2 8
                                                 1 5
                                                 3 7
All this time, the ends keep stepping on the spot, facing front.
As the middles get to position to form a wide set at right angles to original position, on step 12 all turn sharply to face new partner, then all do 2 steps on the spot and 2 steps in, to narrow the set and last two beats are stomp, stomp.

Each side, led by 4 and 7, cast to left, circle out and back to place on 14th beat,
and stomp, stomp on last two.

Side nearest to music do right shoulder back to back round other side
who keep stepping on the spot. They do 1 step to surge across, 2 to get round
partner and into line, 1 on the spot and 4 back to place. Repeat with
other side moving.

All turn out the long way (on stick shoulder) into a clockwise circle and dance off, led by 1.