HELP! I'm stuck...

I'm stuck on a pattern. I can't tell you what it is because it's a Christmas present for MIL who may read this, but this is what the pattern says: Row 28: K across the first 49 sts. Wrap yarn around the 50th st. Place the next 12 sts betweeen the st markers onto a holder. Row 29: P 48 sts, wrapping yarn on the 49th st. Sl the 12 sts between the next set of markers onto another st holder. Cont wrapping in this manner through Row 39 and until 6 sts are wrapped on each edge of the Back Top. So the part where I'm confused is when I get to the end of Row 30. Do I wrap the last stitch again? That doesn't make sense though. I'm so confused. It seems like there is a decrease going on somewhere that I'm missing? Any suggestions would be much appreciated. I need the needles from this project to finish the Debbie Bliss Ribbed Jacket so I don't know what I'm going to knit until I figure this out!