Well played, GRRM, now you have me feeling sorry for Cersei. She has to do a naked walk of shame through the city to atone for sins she confessed to before standing trial for the ones she didn't. Then again, they include having people tortured and killed, so...
She has to do the walk of shame. She does pretty well at first, resolving to hold her head high since none of this really matters and words yelled by onlookers are wind. After falling over a couple of times (and I'm kind of worried about infections from stepping in poo with a wounded foot) she comes to the realisation that the real cost is that she is revealed as just another woman: the facade of royalty is gone. She realises that doing the walk of shame was a mistake.
Wait, what? She had a choice? Ah yes, in the last Cersei chapter Kevan told her that the High Septon "will not release you until you have atoned for your sins." So I suppose she could have avoided this by staying prisoner, presumably forever. In any case she wanted to get back to her son. Who, by the way, Cersei reflects, could have avoided a lot of trouble by not having Ned beheaded. Because the Starks would still be on their side in Winterfell and the other Baratheons would have been disposed of easily. Though presumably it would not have stopped Joffrey from being poisoned, or Tyrion from shooting Tywin. Whatever Cersei thinks, Littlefinger would still be playing his games.
Some boy is shouting about hot pies. What became of Hot Pie?
She goes a bit mad, sees the old hag who made the prophecy about the other, younger and more beautiful queen who will take everything she holds dear. That would be Margaery I suppose.
Then she gets to the castle. Kevan has hidden Tommen away somewhere, but there is a new 8-foot-tall mute in armor to scoop her up. It's Ser Robert Strong, Qyburn's monster (or just a plain resurrected GREGOR), who will be her champion at the trial.
