1–
: 1c lead down and up | cast to 2pl (2c up) (2,1,3,4)
9–
: All turn P RH ; All dance BtoB
17–
: 2c+1c & 3c+4c RHA ; LHA (2,1,3,4)
25–
: End cpls chase 3/4 round cclw **while**{6} middles RHA 1 1/4, forming a set at right angles | All set to P

{{explanation}}
The set has now rotated 1/4 clockwise.  The bottom couple (2c) becomes the next dancing couple