A long way behind me there’s a parked spider, its open door dripping light across the reddish sandy desert. Now I know where I am, but it doesn’t make me feel any better. Beyond the wall I can see the sculpted stone domes and gantries of a famous mausoleum. They loom against the unforgiving sky like the skeletons of abandoned spacecraft. I tiptoe along the path, aware that my information may be misleading; the guardians this place is famous for might not be comatose. The night is chilly, and my coat crackles around me as I walk, fabric rustling uneasily.

The lych-gate is chained shut with an antique padlock, frost-rimed and sand-scoured. It’s the work of a moment to crack the hasp open (I carry a vicious little multitool fitted with a wrist-lock adapter), and then I slip inside and look around.

The third expedition to Mars is the one that everyone remembers, of course. It’s a grisly tale, and a cautionary one. And so we repeat it down the years, at parties and drunken gatherings that need a frisson of fear — the tale of how, after three years on the ground, their orbital return vehicle’s oxidizer tank failed while they were pressurizing it. How they hunkered down with their remaining supplies to await rescue by the relief mission; and how a huge solar flare struck during the relief ship’s launch window, forcing its crew to abandon ship. We tell of the suicides, noble and heroic, determined by lot to stretch the supplies — the murders, too, and the madness, and the resignation and despair as the clocks counted past the point of no return. And we shudder at the arrival of the fourth expedition, three years later, half a year after the food ran out, and what they found; the commander still standing in her pressure suit, propped against a rock to greet her relief, faceplate unlatched beneath the empty sky…

Our Creators were clearly insane. Sending canned primates to Mars was never going to end happily. But theirs was a glorious madness! They actually thought they were going to the stars. And the graveyard custodians, having done their best to honor their charges, reflect it in their own inimitable way.

I sneak inside the drystone walls and along the gravel path. Every pebble is machined to micrometer tolerances, lovingly laid in the bed that divides the carved-sandstone obelisks from the row of statues that memorialize the dead heroes of Greater Indonesia, fallen in the wake of the Indian and Chinese expeditions. Few visit the graveyard, and there has been little wear and tear since the last of our Creators shook the dirt of this planet from their boots and took themselves home to die. Consequently, the sextons have spent the last two centuries elaborating and embellishing the mausoleum. They’ve slowly turned what was once a simple and tasteful rock garden into an outlandish necropolis, a fitting memorial to a dead species’ dream of planetary colonization.

A hundred years ago, any visitor who announced themselves to the sextons would have been made welcome, conducted on a tour of the cemetery, and allowed to meditate or worship as they would. But there have been political problems in recent times, and unwelcome incursions. Grave robbers and genome bandits hoping to find undamaged chromosomal material with their vital sa-RNA and si-RNA sequences intact — even undenatured enzymes — have repeatedly tried to steal the buried mummies of Mars. The graves of heroes have become an attractive nuisance, a magnet for the worst of our kind. The sextons responded by defending it obsessively, in that very special manner that makes ancient and deranged arbeiters with no override so dangerous.

I pass the first impaled skeletons fifty meters in. There are two of them, delicately threaded onto rust-reddened spikes to either side of the gravel path, just before a flight of steps that leads up to a carved waist-high stone balustrade and the first row of tombs. They are child-sized, large-headed chibi grave robbers with gaping eye sockets and cracked jaws locked in a silent scream of rage and frustration. Their flensed arms still twitch their ragged claws at the thin air, for the sextons refuse to pervert their instructions by killing. I slip between them like a ghost, sparing them no sideways glance. Their rescue is not my business; and in any case, after all these years, they will likely be as mad as the jailers who have severed their speech centers and raised them aloft as a dreadful warning.

Huge stone sarcophagi loom to either side of the path, surmounted by heroic statuary: angels in pressure suits stand over the fallen, wings drooping and leading-edge flaps extended. Between them and behind them the sextons have carved a multitude of rough, gnarly columns surmounted by dendritic effusions of tubes and airfoils, as if in imitation of some glade of extinct sessile life-forms. (Plants, that’s what they’re called. Trees. Juliette has studied them, I recall.)

I sneak past empty crypts and petrified trees, following the path past more monumental carvings, stelae of red sandstone bearing signs of abrasion (while the atmosphere is thin and chill, it suffices to blow storms of sand and dust across the graveyard several times in each long Martian year). Presently, my map-fu prompts me to turn along a sunken, narrow side path that leads behind another wall, shielded from the innermost circle of graves (their memorials all carved in the shape of fantastic, archaic spacecraft). I am barely fifty meters from my destination when the skin in the small of my back tenses, a moving wave of irritation nudging me up against the chilled rock surface as I sense vibration through the soles of my feet. Thud. Thud. The sexton’s ominous monopod gait is slow and tentative, cautiously advancing. They can hear through their feet, my employer warned me. If you move, they’ll get a bearing on you. And then they’ll leap.

I’m too close to give up now! But if I move, the sexton will hear me. They’re not fast — not until they get the jump on you — but a hollow dread fills me at the thought of falling into their squamous grasp. In this garden of rest, the screaming wordless living have come to outnumber the dead. They attract quixotic rescuers despite the persistent rumors that the sextons booby-trap the soul chips of their victims. A new fear begins to steal up on me, for the monopod’s concussive stomping has stopped — and I am losing power. Out here on the stony nighttime desert of Mars, heater packs or no, the temperature drops alarmingly; the ground beneath my feet saps energy fast, and the breeze adds a wind-chill that my heavy coat cannot entirely block. If I do not move on and complete my mission, I am in danger of freezing solid — in which state the sextons will discover me sooner or later.

Gravel rattles nearby. A titter of quiet encrypted chatter passes me by. I’m not alone in here tonight, it seems. Of all the bad luck…

A pair of doll-sized ninjas slide past the end of my alleyway in a poisonous glide, pausing briefly to check for surprises. They miss me because I hide in the shadows like a discarded sack of gravel, my skin and hair dialed down to the black of a Martian nighttime shadow — they’re scanning for sextons, not rivals. They belong to Her, of course, and like all of Her little creatures, they are vicious and focused, special-purpose organisms designed for just one task. They’re not here because of me; they seem to be trying to reach the central crypt. That would be a disaster for Jeeves, for She is a jealous mistress. If they get what She wants, they’ll blow the dome behind them, let in the desert sands and the corrosive, superoxidizing dust to wipe the Creator tomb clean of residual replicators — and I’d get the blame.

I hear more brief, encrypted chatter. The sexton on the other side of the wall is motionless, waiting. I can feel its presence like an oppressive weight at the back of my head, its outrage at the intrusion of motion and life into its garden of tranquil death. The ninjas titter mockingly. I close my eyes, blinking away a thin film of ice. Can I triangulate on them…? They use electrosense, true, and I can feel their near-field proximity. They’re just over there —