"The minstrel boy to the war has gone, with his wild-harp slung behind him", sayeth the bard. In this case it's a lute (sounds like `loot' to a barbarian), and he has been snatched from the Morporkian Embassy in Hunghung and carried to the Last Battle.
Cohen the Barbarian and his Silver Horde are feeling old and want to go out in one last epic endeavour. This obviously requires an epic poem, or saga, in commemoration, so Cohen finds a bard to write it. Cohen, unfortunately, is almost uniquely unqualified to adjudicate any poet, bard or musician, and what he gets is a minstrel (not even, as he admits, a very good minstrel).
The Minstrel is working under the enhanced carrot-and-stick system; the carrot being replaced by a fortune in rubies, and the stick by the possibility of Cohen becoming very upset. This is a lot of enhancement. As a barely-qualified minstrel he has no idea how to write a saga and has to be instructed by Cohen in Teutonic reversal of sentence order and the use of words like `rede', `doom' and `spake'.
After enduring horrors known only to barbarian heroes and explorers named Jones, he has plenty of material for a saga burnt uncomfortably into his mind. He also realises simultaneously that nothing worse could happen to him and that the gods will really want everyone to know what happened when they were attacked by the very old man in the fish costume, so he stays with the group for their assault on Dunmanifestin.
When the Silver Horde finally ends with an enormous bang and no whimpering at all, the minstrel throws a fortune in rubies in the snow and realises that he can't write a fitting saga. He has, however become a better minstrel and writes a ballad for the ages. The Minstrel has no name, unless it is Anon.
"No one remembers the singer. The song remains." T.D.J. Pratchett, et al.
Elsewhere in the canon, we are informed that Minstrels and Troubadours are educated and trained at the Fools' Guild in Ankh-Morpork. so this Minstrel would have seen quite a few blood-chilling horrors even before being abducted by the Horde.
A double joke is at work here. The greatest bard in Classical Greece was Orpheus, which translates as Famous of Name - yet nobody remembers what Orpheus was called before he got that title...
Minstrels and troubadours, who are the survival of a time-sanctified tradition of courtly song and music, with its professional dress a relic of that worn six or seven centuries ago, using its own time-hallowed vocabulary of professional terms and its extensive library of approved songs that were number one hits of previous millennia, learn their art at the college of Clowns, Fools, Joculators, Buffoons and Mime-Artists in Ankh-Morpork. Naturally...
It is interesting that this Minstrel was also an accredited diplomat, if only a fairly lowly one, at Ankh-Morpork's embassy in Agatea. This relates well to the accusation frequently levelled at Doctor Whiteface, that Guild graduates who naturally go all over the world to perform their wretched rites are also a very good front for intelligence-gathering and espionage activities. And of course, Vetinari would have had to approve appointments to overseas embassies... proof of this troubadour being fundamentally tough enough to survive as a spy is is provided by the fact that he braves perils with the Silver Horde - and lives....
And at the end, the formerly foppish minstrel is seen transformed, wearing the animal-skins of a barbarian warrior, a sword at his side, and even the light around him taking on the heroic air of the character on the front of a typical Iron Maiden album sleeve... has he discovered heavy metal?