Arya, Hot Pie and Gendry get caught stealing vegetables from a dead man's garden by Lem, Archer/Anguy and Tom of Sevenstreams the singer. After a bit of parley, Arya realises they can't escape the archer, and they go with them to a nearby Inn where they are promised food but I suspect Arya at least will be sold into slavery of some form.
It turns out to be the same Inn visited by Jaime, Brienne and Cleos a couple of chapters earlier. Lem, Archer and Tom were supposed to intercept Jaime and company and steal their horses, but were foiled because Brienne didn't trust the man who is not an innkeeper and chose a different route from the one he advised.
Sure enough, after being fed, the band of outlaws offer Arya a promissory note in exchange for their horses. The note is probably worthless since there is no gold (imagine someone on 21st century Earth falling for that! Err...) but Arya thinks they're going to lose their horses anyway, so she offers them in exchange for Brienne's boat that she's seen outside.
Just then some riders turn up, who turn out to include Harwin, who used to lead her pony around the yard. He recognises her and announces to the room that she is Arya Stark, daughter of the Hand. So perhaps these really are "king's men" still loyal to the ghost of Robert and his hand.
