The famous legend is based on real facts, despite evidently faked in the conclusion and consequences... it tells about the Etruscans siege of Rome and the young Roman Caius Mutius, who sneaked in the Etruscan camp to kill the Etruscan King Porsena, a killing attempt that failed because Mutius mistaken the scribe for the King himself, due the scribe's rich luxury clothes.
Immediately arrested for the murder of the scribe, Mutius then was bring in front to Porsena, and he put his right hand in a brazier to "punish the hand that failed", and apparently Porsena forgave him for his bravery.
To thank the merciful Porsena, Mutius warned him about the 300 other young Romans ready to attempt to murder him... at this point, according to the Roman legend, Porsena was so impressd to abandon the siege of Rome and retreat.
There are several interpretations, however Porsena didn't seem to be really impressed at all, as the historicians agree he actually conquered Rome after all, and ruled the town himself for quite a while, instead to restore Lucius Tarquinus Superbus, who was the last legitimate Etruscan king of Rome and just dethroned.
And from that moment Caius Mutius was called "Scaevola" which means "left handed".
Further than King Lars Porsena and Caius Mutius, I imagined was present also Arruns Porsena (Arunte-Arnth Pursena) unsheating the Machaira and ready to protect his father.
And of course the two Guards that arrested Mutius.
In the background of the scene of course, in another room of the large King's tent, the murdered Scribe couldn't be missing!