Interactive case files · single-player deduction
One line. Inside, and outside.
A city was sealed off one night for reasons nobody explained. Emergency crews put up cordons between blocks; afterwards only scattered patrol counts and call records were recovered. Reconstruct the cordon that really stood that night — then see who was inside, who was outside, and whose story can't be true.
- The cordon is one complete loop — no gaps, no crossings, no branches.
- A number on a block = how many of its sides carry a barrier.
- Testimonies must hold — they tell you who was inside and who was outside.
The Night Plague
Three months ago a sickness appeared that only stirs after dark. By day nothing shows; after nightfall the coughing starts, and within two days it has run through a whole building.
The Emergency Bureau's answer was simple: the moment a block reports a case at night, seal it with barriers. Inside, fourteen days of quarantine — no work, no leaving. Outside, life goes on.
So everyone has a reason to lie. Some say they were outside to keep their jobs; some say they never left so they can stay with family inside; and some cross the line at night to deliver medicine — or something else.
Afterwards, all that remains are railing counts scrawled by patrol officers and a few call records. Investigator Shen Yi — that's you — has to draw each night's cordon back.
Chapter 1 · Patrol Records
Only numbers and one closed loop. Learn to draw the cordon.- Case 0102:17
First Night at the Old Harbor
Old Harbor · Dock blocks · 5×5
The first file after the incident. Patrol officers noted railing counts outside a few blocks; the rest of the record dissolved in the rain. Draw the cordon back first.
Not started - Case 0202:33
Railings on Canal Street
Canal Street · Warehouse belt · 5×5
The second patrol record comes from Canal Street. The counts are sparser this time and some blocks have nothing at all. Using "definitely none" to rule out impossible edges is much faster.
🔒 Finish the previous case first - Case 0302:44
The Vacant Lot
Old Harbor · Around the vacant lot · 5×5
The third patrol record is numbers only, with no note to explain them. Once the loop closes you can see it: a lot inside the cordon that was never entered on any map.
🔒 Finish the previous case first - Case 0402:51
The Altered Log
Old Harbor · Patrol station · 5×5
The pencil marks on this patrol sheet have been rubbed out and written over — cleanly. The numbers still admit exactly one loop; it is simply wider than the one dispatch reported.
🔒 Finish the previous case first - Case 0502:58
The Signal Tower
North Bank · Around the signal tower · 5×5
The blocks around the signal tower were sealed tight. Only a few 3s and a string of 1s survive. This loop takes a long detour.
🔒 Finish the previous case first
Chapter 2 · Inside and Outside
Testimonies start pointing at specific blocks.- Case 0603:20
The Pharmacy and the Station
Central · Station square · 5×5
From this file on there are testimonies alongside the patrol counts. The pharmacy's night clerk says he was sealed inside; the station's PA log shows the forecourt stayed open. Statements like these tell you directly which blocks lie inside the loop.
🔒 Finish the previous case first - Case 0703:47
The Night Market
South District · Night market · 5×5
The lockdown began as the stalls were packing up. Xiao Lin, a vendor, says he was trapped inside; the warehouse keeper says the warehouse stayed outside the whole time. Those two statements plus the patrol counts should pin the loop down.
🔒 Finish the previous case first - Case 0803:52
The Unlisted Warehouse
South District · Behind the goods yard · 6×6
The warehouse Xiao Lin mentioned is on no register. Its keeper will say only one thing: the shed is inside the railings. The goods-yard gate carried no barrier that night, and the tyre tracks run from it down to the river.
🔒 Finish the previous case first - Case 0903:56
The South Clinic
South District · In front of the clinic · 6×6
The trail of antipyretics leads to a clinic in the South District. It appears on no case bulletin, yet it was sealed inside that night. The duty doctor says he never left the consulting room.
🔒 Finish the previous case first - Case 1004:00
The Delivery Route
South District · Back lanes · 6×6
Put the three statements together: the shed inside, the lane outside, the clinic inside again. For the first time the route Chen Bei walked that night takes shape.
🔒 Finish the previous case first
Chapter 3 · Same Side, Other Side
Numbers and testimonies confirm each other.- Case 1104:05
Clinic Row
East District · Clinic Row · 6×6
Three people were near Clinic Row when the lockdown came. Call records show A-Qing and the doctor on the same side of the cordon, and the courier across the line from the doctor. Nobody says outright whether they were inside or outside — you have to work that out.
🔒 Finish the previous case first - Case 1204:30
The Ferry Terminal
West Harbor · Ferry terminal · 6×6
The boarding record of the last ferry is missing. The reporter and the night watchman were on opposite sides of the cordon; the reporter and the bar were on the same side. A larger map, and fewer numbers.
🔒 Finish the previous case first - Case 1304:38
The Same Side
East District · Back of Clinic Row · 6×6
After Clinic Row two more names surface in the call records. A-Qing and the doctor were on the same side; A-Qing and the courier were cut off by the cordon. Nobody says outright whether they were inside or out — a position only tells you who has no barrier between them.
🔒 Finish the previous case first - Case 1404:47
The Gangway
West Harbor · Ferry gangway · 6×6
One name is missing from the boarding record, and there is an extra pair of footprints on the gangway. The captain and the reporter were on the same side; the reporter and the night watchman were separated by the cordon. The watchman insists he stayed outside the line all night.
🔒 Finish the previous case first - Case 1504:56
The Unrecorded Route
West Harbor · Outer edge of the cordon · 6×6
Lay every relation on top of the others and only one route survives: the courier and the captain on the same side, the watchman opposite. The watchman says he never left his post — and he didn't. He had simply mistaken where the line ran.
🔒 Finish the previous case first
Chapter 4 · The Lie
Some statements are false — sometimes more than one.- Case 1605:12
The Cathedral Bell
Old Town · Cathedral square · 6×6
Four statements, exactly one of them false. Old Zhou, A-Zhen and the captain all claim they were in the safe zone; the bell-tower log is in the file too. Draw the cordon, then point out who lied.
🔒 Finish the previous case first - Case 1705:19
The First Lie
Central · Behind the pharmacy · 6×6
The first record pulled from the file is the pharmacy's. Zhou Ming, the night clerk, says he was outside that night; Dr. Gu Lan says she was inside; the archivist Old Xu says he was with Zhou Ming throughout. One of the four statements is false — and it is the earliest one spoken.
🔒 Finish the previous case first - Case 1805:27
Block Zero
Old Town · Block Zero · 6×6
The second record points at a block that does not exist on any official map. Old Xu says he was outside the cordon that night; but A-Qing and Zhou Ming were both inside, and Old Xu's signature appears on every patrol sheet filed that day.
🔒 Finish the previous case first - Case 1905:40
Five Statements
Old Town · West of the cathedral · 6×6
The third record carries five statements, two of them false — the only time the whole file contains two lies at once. Old Xu, Old Zhou, A-Zhen, the bell tower and the night watchman: not one of the five is entirely clean.
🔒 Finish the previous case first - Case 2005:55
Shen Yi's Choice
Old Town · End of the cordon · 6×6
The last record was written by Shen Yi himself. Captain Qi Yue was on his side; the watchman Old Fang was opposite; Block Zero was inside — and Old Xu says he was outside. One of the four statements is false, and this time Shen Yi knows the man who made it.
🔒 Finish the previous case first