Set: Probably Pre-Ciri, Possibly Pre-Yennefer, doesn't really matter. This is very much non-canon.
Please keep in mind that for some bits of this story certain characters *cough*Jaskier*cough* are lying through their teeth, but I'll try to make it clear what is and isn't actually happening.
Also note, this is alternating chapters of humor and angst; the humor is Very silly and the angst gets Very angsty, so read carefully.
The cage was small, the cuffs were tight, and the men were thoroughly incompetent. In short, Geralt of Rivera was having a shit day. The hardened group of ex-mercenaries were idiots, but had managed to get the drop on Geralt after a fight gone bad with a few too many drowners. Said morons were now attempting to turn him in to a mage a few counties over for a bounty. While this might normally prove a dangerous situation for a lone Witcher, Geralt had gotten enough healing potion in him to be recovered, if slightly sore. His captors were likewise unaware that the 'dimeritium' cuffs they had been equipped with were some form of cheap tin, and their 'enchanted spell-cage' was a thin wooden crate.
Geralt was nonetheless going along with this, as it was the easiest way to track down whoever was dumb enough to go asking for trouble (IE witchers). Roach was being treated well, and they hadn't opened the crate (equipped with small holes on the bottom for the necessary arrangements when keeping a prisoner) since stuffing him in there, so all in all it could conceivably be worse. Geralt normally met up with the bard this time of year, though, so the sooner they got where they were going, the better. There was no telling what kind of trouble Jaskier was getting up to roaming the continent unsupervised.
Almost as if his thoughts had summoned it, Geralt's ears picked up the sound of humming and the twangy bounce of a lute-case. He groaned audibly. If there was another minstrel in a hundred leagues who would be wandering blithely thorough a monster-infested forest alone, he would eat his boots. He cocked his head for a closer listen and revised his thought; Jaskier's heart-rate was high, even for him, and his humming had a frantic edge. Lost? Hurt? The Witcher scented the air through the small cracks in the boards and caught a whiff of blood as the wind changed. The cuffs were broken instantly, before Geralt had made a conscious decision, and he had already moved forward as though to break through the wooden crate before he checked himself. He didn't know what the situation was. If the mercenaries had ranged weapons, Jaskier could be put in danger by his acting rashly.
Unfortunately it seemed the sound of snapping metal had set the mercenaries on edge. They had almost finished setting up camp, still on their feet after a day of traveling, and had now fallen suspiciously silent. Geralt's hearing was sharper than any man's, and the bard might have passed unnoticed...if he hadn't picked that moment to start whistling. Geralt sighed. He used the end of the metal cuffs to noiselessly pry open the seam of his box slightly, creating a hole to look out of, and stared at the bushes where-from issued a jaunty tune.
The mercenaries had their backs to Geralt's crate, but several were armed with crossbows pointing uncomfortably towards the sound of the incoming troublemaker. At a hand signal from the leader of the group, one of the men stepped forward, shoving aside the foliage, and demanding "who goes there?" The answer was a very familiar scream, the volume and harmonics of which were unparalleled in the field of demonstrative terror. Geralt could attest that it could carry for miles, and hearing it at a short range was enough to startle the man back as a torn and dirty, but still colorful figure burst through the greenery. For a moment, no one moved, the men taking in the sight of a courtly bard covered in filth and scratch marks.
"Oh no!" shouted Jaskier, somewhat unnecessarily in Geralt's opinion. "This is awful!" he continued. "Just awful!" he added, no doubt about to start going on and on about how imperiled he was. "You're in terrible danger!" Yes, thought Geralt with a sigh, sounds about right… wait. Had the bard just said 'you're' in danger? As in, the mercenaries? The clearly armed, trained fighters, who outnumbered him six-to-one? What?