Bones of birds buried in a ditch. Rain falls upon the ditch and great puddles are formed. A passing pig roots in the puddles for chewables. The pig uproots the bird bones. Detective Captain Cargpan is called in to investigate. He does not immediately recognise the bones as being bones of birds. His top forensics wallah is sick in bed. The rest of the team are on a seaside outing. Cargpan leaps to the conclusion that he has found the bones of a homunculus. He rounds up a few known criminals and roughs them up back at the station. Not a one of them confesses. Cargpan trawls through a logbook of missing homunculi. He tries to tally up locations and dates. He taps one of the bird bones against a saucer. From the sound it makes he guesses it to be twenty years old. But no homunculi went missing twenty years ago. He lights a cigarette and mooches about the deserted police station canteen in the middle of the night.

In a spinney a long way away a miscreant is up to something. The miscreant is surrounded by feathers. Blood is dribbling from his mouth.

In the morning the forensics wallah is worse. She is taken to a clinic by a fast loud ambulance. The rest of her team are trapped at the seaside. Detective Captain Cargpan wakes up on a bench in the canteen. He stumbles to the cells and roughs up a ne’er-do-well. Upstairs, he throws the missing homunculi logbook across his office. He returns to the canteen for many, many sausages. He kneels in the chapel and cries out to God. Cargpan is a Muggletonian. He lines up the tiny bones on his desk and counts them and tags them with tags. He returns to the ditch for a stakeout.

The miscreant hobbles out of the spinney. He has wiped the blood off his lips and chin with a rag. He is carrying a suspicious carrier bag. He waits at the bus stop.

Detective Captain Cargpan trains his night vision goggles on the ditch. He has commandeered a bird hide. He roughed up the birdists who were there when he arrived and sent them packing. The rain pours down, creating fresh puddles in the ditch. Cargpan slurps cocoa from a flask confiscated from the birdists. He wants more sausages, but there are none to be had.

The miscreant is aboard the bus. It is hurtling along the lanes towards the field where the ditch is. In the darkness, the driver loses control and the bus plunges down a chasm. It is swallowed up in the sopping wet mud at the bottom of the chasm.

When Detective Captain Cargpan returns to the station he sees a forensics locum. His wallah has taken a turn for the worse. The bigwigs have sent the locum to replace her for the time being. The locum tells Cargpan that the bones lined up on his desk are the bones of birds. Cargpan thumps his fist against his own forehead. A minion runs in to the room to tell Cargpan that a bus has inexplicably vanished. This will be his next case.

In the spinney, from underneath a pile of bloody feathers, a homunculus emerges. It blinks and cackles and scampers away, leaving a trail of weird gas.