Candil Station, in orbit around Mars, the year 2187.
On Candil Station, nothing that is said is ever lost. BIBA, the station’s librarian, archives books, reports and, above all, voices. Every sentence anyone speaks to her is stored on her shelves, with its date, its time and the place where it was said. She has two rules written into her program: she never says anything false, and she never lends what nobody asks for. Listening to someone else’s recordings requires archive clearance, and on Candil only the person in command has it.
Noa Ibarra, an inspector, arrived from Mars six days after the death of Bastián Oria, the oxygen engineer. Leire, the doctor, had found him in Airlock 3, wearing his suit but no helmet. Commander Mireia’s report said “accident”. It added that since the blackout of 2 March, when the station spent a whole hour in the dark, with no lights and no clocks, several systems had been failing. But Noa hadn’t come for the report. Two days before he died, Bastián had written to her: “The oxygen figures don’t add up. Come in person.”
The commander received her on the bridge, the room from which Candil is run and every one of its doors is opened. “The case is closed,” she said. “That night I was here, on duty, with two officers. If you want someone to blame, talk to Goyo. He’s head of maintenance, the only one who knows how to open an airlock without leaving a trace. And the maintenance log for that night is empty.”
Goyo had no alibi, or so it seemed. But BIBA had kept a sentence of his: at 03:10, two minutes before the airlock opened, someone with his voice had spoken to her from the reading room. Noa went down there. It was a small room, with four armchairs and a huge clock above the door. “BIBA, what did Goyo say to you at 03:10?” “‘What time is it?’”
“Was Goyo in the reading room?” “I don’t know. I have no eyes, only ears. I received his voice.” “Had you heard that same sentence before, in that same voice?” There was a short silence, like someone searching a very high shelf. “Yes. On 2 March, at 11:40, in the canteen. It is identical: the same tone, the same pauses, the same cough at the end.”
Nobody says a sentence exactly the same way twice. A recording does. Noa went to see Goyo in his cabin. She expected excuses and found a tired man. “The reading room? I didn’t leave this cabin that night. I was alone, so I can’t prove it. I’m sorry, Inspector: I have no alibi.”
Noa went back to the library and sat down under the clock. She thought about the sentence at 03:10: who could have taken it from BIBA’s shelves, and why. Then she asked the one question nobody had asked. “BIBA, who has listened to the recording from 2 March?” “Only one person,” the voice replied. And this time Noa already knew which name she was about to hear.
Activities
1 Detective Inference
Who opened the airlock where Bastián died? Tick the correct hypothesis.
- a) Goyo, who made himself a fake alibi with a recording of his own voice.
- ✓b) Commander Mireia, who opened the airlock from the bridge and used Goyo’s voice to frame him.
- c) Leire, the doctor, who found the body and could have been in the airlock before anyone else.
- d) Nobody: it was an airlock fault, like so many others since the blackout.
Which clue proves it? Copy or summarise the clue from the text that proves it.
Correct hypothesis: b). That’s it: the fake alibi didn’t protect Goyo, it pointed at him. And only she could have set the trap.
Key clue: “To play Goyo’s sentence, someone had to listen to it in the archive, and only the person in command has that clearance.” That’s the proof: only someone with archive clearance could take the 2 March recording off BIBA’s shelves, and that is the commander.
2 The Loom Order of events
Put the events in order, starting with the earliest. Write the order number (1, 2, 3…) in each box.
- 5 The commander receives Noa on the bridge.
- 6 Noa asks who has listened to the 2 March recording.
- 1 In the dark, Goyo asks in the canteen what time it is.
- 4 Leire finds Bastián in Airlock 3.
- 2 Bastián warns Noa that the oxygen figures don’t add up.
- 3 Goyo’s voice is heard in the empty reading room.
Correct order:
- In the dark, Goyo asks in the canteen what time it is.
- Bastián warns Noa that the oxygen figures don’t add up.
- Goyo’s voice is heard in the empty reading room.
- Leire finds Bastián in Airlock 3.
- The commander receives Noa on the bridge.
- Noa asks who has listened to the 2 March recording.
The original sentence is from the blackout on 2 March. Bastián writes to Noa two days before he dies. On the night of his death the voice is heard at 03:10, and then the body is found. Six days later Noa arrives: first she talks to the commander and, at the end, asks the decisive question.
3 The Missing Page Coherence
What does BIBA answer next, consistent with the story? Tick only one option.
- a) She says Goyo’s name: he listened to his own recording to prepare the alibi.
- b) She refuses to answer, because she never lends what nobody asks for.
- ✓c) She says the name of Commander Mireia, the only person on Candil with archive clearance.
- d) She replies that, in fact, nobody has ever listened to that recording.
Answer: c). It fits: only the person in command can listen to other people’s recordings, which is why Noa already knew the name she would hear.
- a) Listening to recordings requires archive clearance, and only the person in command has it. Goyo is head of maintenance.
- b) This time someone has asked: Noa has asked the exact question, and BIBA can’t lie or hold back an answer that’s been requested.
- d) BIBA doesn’t lie, and she has already said that “only one person” listened to it.
4 Spot the Contradiction Literal reading
Three statements don’t fit the story. Put an X next to the 3 statements that don’t fit the text.
- a) Bastián was found in Airlock 3 wearing his suit but no helmet.That’s how Leire, the doctor, found him.
- ✗b) Goyo’s voice spoke to BIBA from the bridge.It spoke from the reading room; the commander was on the bridge.
- c) BIBA has no eyes: she only receives voices.That’s why she doesn’t know whether Goyo was really in the reading room.
- ✗d) Goyo claimed he was in the reading room at 03:10.He said the opposite: that he didn’t leave his cabin and had no alibi.
- e) The commander said she was on duty that night with two officers.And that the case was closed.
- ✗f) Goyo’s two sentences had a different tone.They were identical: the same tone, the same pauses and the same cough.
5 The Gallery Visualisation
In the game you choose the illustration that answers this question: “Which picture shows the canteen on 2 March at 11:40, when Goyo really asked the time?”. Here, you draw it yourself, with every detail the text gives you.
What should appear: In the dark, with no lights or clocks, and Goyo asking: that’s why, that time, the question made sense.
Reward drawings that include the details from the text, not artistic skill.
Ending
To read aloud once the answers have been checked.
Commander Mireia had been falsifying the oxygen reports for months: if the leak came to light, the station would be closed and she would lose her command. Bastián found out. That night Mireia never left the bridge, and her two officers were right to swear to it: she didn’t need to leave, because every door on Candil can be opened from there. She typed the order among a hundred others, wiped the maintenance log and, through the reading-room speakers, played a sentence of Goyo’s she had taken from the archive: “What time is it?”
It wasn’t an alibi for her, but a trap for him. It had to look so fake that any inspector would spot it and think: “Goyo built himself an alibi, so he’s guilty.” One detail went wrong. Goyo knew nothing about that sentence, so he didn’t defend it. A guilty man would have sworn he was in the reading room. He told the truth: that he had no alibi.
The original sentence was innocent. On 2 March, during the blackout, with the station dark and the clocks off, it was the only moment on Candil when it made sense to ask the time. And only someone with archive clearance could have listened to it and copied it.
Replay attacks really exist: voice systems detect them by comparing each sentence with those already recorded, because a person never says a sentence exactly the same way twice.
Suggested marking
Each activity is worth 2 points (10 in total). In 1, one point for the hypothesis and one for the clue. In 2, give one point if only a couple of events are swapped. In 4, half a point for each correct cross and minus half a point for each true statement crossed out.