Serenity docks at Bernadette station – an environmentally sealed base on the non-terraformed Bernadette moon, staging location for ships of settlers headed for the border planets. In addition to the cargo-run of settler’s supplies, a man books passage on Serenity under the name "Mr Shansu". He’s odd. He carries himself with a world weariness and has very few possessions: a leather bag and a long steel sword, dressed in ragged flowing brown robes with hood that hangs down over his face allowing just his chin to be visible. The robe is made up from multiple layers of porous hessian-like fabric, giving glimpses of pale skin under the hood and dark, metallic, band covering his eyes.
When they get to the coordinates the man specified there’s only deep, empty, black space. Mal was expecting another ship. While he’s confused in the cockpit talking with Wash and Zoe, Kaylee see the stranger getting into the airlock carrying a small coloured glass jar that was in his bag and she tries to disable the cycle but is unable … she races up to the cockpit to tell Mal.
The man walks outside onto the hull of the ship without a spacesuit. Shepherd Book joins him moments later and begins a funeral liturgy. The jar is opened and the stranger scatters fine grey ashes into space. Once back inside the pair are confronted by Mal … and the man admits to being "very old" and that you have to get very specific on the method of death if you want to kill him. Mal shoots him, and promises to drop him off at the border world – final destination for the cargo containers. The man spends the return trip in his room, recovering.
After dinner Mal confronts Shepherd Book who, in explanation, reads to the crew from his bible, saying that the first passage was from the apocalypse of St. John
I turned around to see the voice that was speaking to me. And when I turned I saw seven golden lampstands, and among the lampstands was someone “like a son of man,” dressed in a robe reaching down to his feet and with a golden sash around his chest. His head and hair were white like wool, as white as snow, and his eyes were like blazing fire. His feet were like bronze glowing in a furnace, and his voice was like the sound of rushing waters. In his right hand he held seven stars, and out of his mouth came a sharp double-edged sword. His face was like the sun shining in all its brilliance.
He went on to explain that the Isaiarite sect, thought to be extinct, took the passage literally. He explained that Isaiarites had little sense of irony or understanding of metaphor, and a great propensity to take things out of context. Book began reading again,
In the year that King Uzziah died, I saw the Lord seated on a throne, high and exalted, and the train of his robe filled the temple. Above him were seraphs, each with six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying. And they were calling to one another:
”Holy, holy, holy is the LORD Almighty;
the whole earth is full of his glory.”
At the sound of their voices the doorposts and thresholds shook and the temple was filled with smoke.
“Woe to me!” I cried. “I am ruined! For I am a man of unclean lips, and I live among a people of unclean lips, and my eyes have seen the King, the LORD Almighty.”
Then one of the seraphs flew to me with a live coal in his hand, which he had taken with tongs from the altar. With it he touched my mouth and said, “See, this has touched your lips; your guilt is taken away and your sin atoned for.”
He explained that the metal band across the eyes had both symbolic and functional meaning; in the symbolic sense, it offered blindness to general members of the order, but for the true holymen, it covered true self-inflicted blindness. The Isaiarite sect handled live coals in much the same way as fringe movements in the old days handled snakes as a religious rite; burns, pain and scarring were elevated to being a means of purification and atonement for past sins committed.
Kaylee stops in on the stranger on her way back to her room after dinner and finds him laying on his bed extremely pale, not breathing, without a heartbeat. A medical emergency ensues, Simon removes the metal band on the stranger’s face – empty eye sockets containing ash and charcoal. All attempts to rouse the man are met with failure. They leave him covered with a sheet and turn in for the night, Jayne claiming dibs on the man’s sword for his collection.
The body is gone next morning. Robes are folded neatly and the metal face band sat on top of them. A search ends up finding him in the hold practicing with the sword, bare chested, eyes regrown, hairless with pants stolen from Simon. When asked, Simon admits that peroxide is also missing from the medical supplies. The stranger hands Mal back the bullet rubbing the spot where an entry wound should have been, complaining of a slight residual ache.
The stranger is dropped off at "the next stop" along with the cargo containers, his hair now regrown and bleached with the stolen peroxide, seemingly not caring where the journey takes him next, but very careful to leave under the cover of night.
"Next time there’s an apocalypse, the powers that be know where to find me"