The luxury liner H.M.S. Aquinas sped among the stars, its great engines devouring distance and defying time. Each porthole offered a lurid glimpse of that colossal pointillist work which God Himself has painted in subtle yet searing star-points upon the black canvas of creation, too vast for any critic ever to step back and see entire. In the main lounge, however, the ship�s passengers were already jaded by the splendour of the suns and had found a new distraction. For Astron, high celebrant of the newest religion, was weaving dazzling circles of rhetoric around a shabby, blinking priest of the oldest.

�Did not a great writer once say that the interstellar spaces are God�s quarantine regulations? I think the blight He had in mind was the blight of men like this, crabbed and joyless celibates who spread their poisoned doctrines of guilt and fear from planet to planet, world after world growing grey with their breath��

The crabbed and joyless object of these attentions sipped wine and contrived to look remarkably cheerful. Father Brown was travelling from his parish of Cobhole in England on Old Earth as an emissary to the colony world Pavonia III, where Astron planned to harvest countless converts and (it is to be assumed) decidedly countable cash donations for his Universal Temple of Fire.

�For the Church of Fire pays heed to its handmaid Science, and sheds the mouldy baggage of superstition. The living Church of Fire gives respect to the atomic blaze at the heart of every sun, to the divine laws of supersymmetry and chaos theory; the dying church of superstition had nothing to say about either at Vatican III.�

The little, pudding-faced priest murmured: �We never needed chaos theory to know that the cycles of evil run ever smaller and smaller down the scales of measurement, yet always dreadfully self-similar.� But it passed unheeded.

Astron boomed on, remarking that those who obstructed the universal Light would be struck down by the spear of the sun. Indeed he looked every inch the pagan god, with his great height, craggy features and flowing flaxen hair now streaked with silver. A golden sunburst of a ring gleamed on his finger. His acolyte Simon Traill was yet more handsome though less vocal, perhaps a little embarrassed at Astron�s taunting. Both wore plain robes of purest white. The group that pressed around consisted chiefly of women; Father Brown noted with interest that red-haired Elizabeth Brayne, whom he knew to be the billionaire heiress of Brayne Interplanetary, pressed closest of all and close in particular to young Traill. She wore the dangerous look of a woman who thinks she knows her own mind.

�Damn them,� said a voice at Brown�s ear. �Pardon me, Father. But you heard that Astron saying what he thinks of celibacy. He chews women up and spits out the pieces. See Signora Maroni back there with a face like thunder? She�s a bit long in the tooth for Mr. Precious Astron, but for the first two nights of this trip she had something he wanted. Now that something�s in his blasted Temple fund, and�Well, perhaps you wouldn�t understand.�

�Oh, stories like this do occasionally crop up in the confessional,� said the dumpling-faced priest vaguely, eyeing the dark young man. John Horne was a mining engineer, who until now had talked of nothing but Pavonia III�s bauxite and the cargo of advanced survey and digging equipment that was travelling out with him. Father Brown knew the generous wrath of simple men, and tried to spread a little calm by enquiring about the space-walk in which several of the passengers had indulged earlier.

Though allowing himself to be diverted for a little time, Horne presently said, �Don�t you feel a shade hot under the dog-collar when Astron needles you about his Religion of Science and how outdated you are?�

�Oh yes, science progresses most remarkably,� said Father Brown with bumbling enthusiasm. �In Sir Isaac Newton�s mechanics, you know, it was the three-body problem that didn�t have any general solution. Then came Relativity and it was the two-body problem that was troublesome. After that, Quantum Theory found all these complications in the one-body problem, a single particle; and now they tell me that relativistic quantum field theory is stuck at the nobody problem, the vacuum itself. I can hardly wait to hear what tremendous step comes next.�

Horne looked at him a little uncertainly.

A silvery chime sounded. �Attention, attention. This is the captain speaking. Dinner will be served at six bells. Shortly beforehand there will be a course correction with a temporary boost of acceleration from five-eighths to fifteen-sixteenths g.�

�I go,� said Astron with a kind of stately anger, drawing himself up to his full, impressive height and pulling the deep white cowl of the robe over his head. �I go to be alone and meditate over the Sacred Flame.� With Traill cowled likewise in his wake, he stalked gigantically from the lounge.

�That makes me madder than anything,� Horne said gloomily, beginning to amble in the general direction of Elizabeth Brayne. �No pipes, no cigarettes, that�s an iron rule�and he manages to wangle an eternal flame in his ruddy stateroom. The safety officer would like to kill him.�

But it was not the safety officer who came under suspicion when the news raced through the Aquinas like leaves in a mad March wind: that a third lieutenant making final checks before the course change had used a master key and found that great robed figure slumped over the brazier of the Universal Flame, face charred and flowing hair gone to smoke, a scientific seeker who had solved the no-body problem at last.

By a happy chance, ship security had been contracted out to the agency of M. Hercule Flambeau, one-time master criminal and an old friend of Father Brown, who set to in a frenzy of Gallic fervour. Knowing the pudgy little priest�s power of insight, Flambeau invited him at once to the chamber of death. It was a stark and austere stateroom, distinguished by the wide brazier (its gas flame now extinguished) and the terrible figure that the third lieutenant had dragged from the fire.

�He seems to have bent over his wretched flame and prayed, or whatever mumbo-jumbo the cult of Fire uses for prayer,� mused Father Brown. �Better for him to have looked up and not down, and savoured the stars through that porthole� Even the stars look twisted in this accursed place. Might he have died naturally and fallen? That would be ugly enough, but not devilish.�

The tall Flambeau drew out a slip of computer paper. �My friend, we know to distrust coincidence. The acolyte Traill is nowhere to be found, and the ship�s records say the nearest airlock has cycled just once, outwards, since Astron left the main lounge an hour ago. Some avenger has made a clean sweep of the Church of Fire�s mission: one dead in a locked room, one jettisoned. And half the women and all the men out there might have had a potent motive. We�re carrying members of rival cults too�the Club of Queer Trades, the Dead Men�s Shoes Society, the Ten Teacups, and heaven knows what else. But how in God�s name could any of them get in here?�

�Don�t forget the crabbed priesthood that blights human souls,� said the smaller man earnestly. �Astron was last seen attacking it with a will, and its representative has an obviously criminal face. Ecce homo.� He tapped himself on the chest.

�Father Brown, I cannot believe you did this thing.�

�Well, in confidence, I�ll admit to you that I didn�t.� He bustled curiously about the room, blinking at the oversized bed and peering again through the viewport as though the stars themselves held some elusive clue. Last of all he studied the robed corpse�s ruined face and pale hands, and shuddered.

�The spear of the sun,� he muttered to himself. �Astron threatened his enemies with the spear of the sun. And where does a wise man hide a spear?�

�In an armoury, I suppose,� said Flambeau in a low voice.

�In poor foolish William Blake�s armoury. You remember, All the stars threw down their spears? But the angel Ithuriel also carries a spear. Excuse me, I know I�m rambling, but I can see half of it, just half�� Father Brown stood stock still with hands pressed into his screwed-up eyes. At last he said: �You thought I shuddered at that wreck of a face. I shuddered at the hands.�

�But there is nothing to see�no mark on the hands.�

�There is nothing. And there should be a great sunburst ring. They are younger hands than Astron�s, when you look. It is the acolyte Traill who lies there.�

Flambeau gaped. �But that can�t be. It turns everything topsy-turvy; it makes the whole case the wrong shape.�

�So was that equation,� said Father Brown gently. �And we survived even that equation. But I need one further fact.� He scribbled on a slip of paper and folded it. �Have one of your men show this to John Horne. A reply is expected.�

Wordlessly, Flambeau pressed a stud and did what was asked. �Horne,� he said when the two friends were alone again. �The one who fancies Miss Brayne and didn�t like her interest in men with white robes. Is he your choice for the dock?�

�No. For the witness-box.� Father Brown sat on the edge of the bed, the dinginess of his cassock highlighted by the expanse of white satin quilting, his stubby legs not quite reaching the deck plates. �I think this story begins with young Horne prattling over dinner about his cargo. So I asked whether a piece of his equipment was missing. Come now: when you think of fiery death in a locked stateroom, what does mining and surveying gear suggest to you?�

�Nothing but moonshine,� said Flambeau with sarcasm. �I do assure you that each hull plate and bulkhead has been carefully inspected for any trace of a four-foot mineshaft through which a murderer might crawl.�

�That�s the whole sad story. Even when you look at it you can�t see it: but every stateroom of this vessel contains a Judas window through which death can strike. And�� Brown�s muddy eyes widened suddenly. �Of course! The spear of the sun is two-edged. My friend, I predict� I predict that you will never make an arrest.�

As Flambeau arose with an oath, the communicator on his wrist crackled. �What? The answer is yes? Father, the answer is yes.�

�Then let me tell you the story,� said the priest. �The great Astron devoured woman after woman, but most of all he craved the women who did not crave him. For as I saw, Elizabeth Brayne was taken with Simon Traill. And Astron left the room in anger.

�I fancy it was his practice to have Traill watch over the ritual flame for him, while another cowled figure glided out upon certain assignations. But this time Astron�s assignation was a darker one. He knew where to find the pressure suits: there was a space-walking party a few watches ago. He knew that in Horne�s cargo he would find his spear.�

�Which is�?�

�A laser.�

Father Brown continued dreamily after a sort of thunderous silence. �Picture Astron floating a little way outside that porthole, a wide-open window for his frightful, insubstantial bolt. Picture his unknowing rival Traill bent over the flame, struck in the face, falling dead across the brazier which would slowly burn away every mark of how he died.�

�Name of a name,� cried Flambeau. �He is still out there. We shall have him yet!�

�You will never have him.� Father Brown shook his head slowly. �The spear, I said, is two-edged. Oh, these strong and simple Stoics with their great bold ideas! Astron called us impractical and superstitious, but lacked even the little smattering of quantum electrodynamics that every seminarian picks up along with his Latin and his St. Augustine. He thought the crystal of the port purely transparent, Flambeau: but there is diffraction, my friend, and there is partial reflection. And even as it slew his victim, the spear of the sun rebounded to strike the murderer blind.� The little priest shivered. �Yes, the humour of God can be cruel. Astron�s easy arrogance saw the motes in all men�s eyes, and now at last found the beam in his own�.

�Picture him now, flinging his suit this way and that with those clever little gas-jets, with nightmare pressing in as he realizes he cannot find the ship in the endless dark. And then comes the course correction and he has no more chance. And now that void which he worshipped in his heart has become his vast sarcophagus.�

�I think,� said Flambeau slowly, �that brandy would be a good thing. Mother of God. All that from a missing ring.�

�Not only that.� said Father Brown, �The viewport crystal was slightly distorted by the heat of the beam�s passage. I said the stars looked twisted, but you thought I was being sentimental.�