‘What?’ Dru Cardenas demands, his voice jumpy. ‘Are we under attack?’
He looks like he desperately wants to shoot something with his shiny new Leyden cannon. Even by Shark standards, Dru is trigger-happy. I decide I should give him a task that does not involve weapons.
‘There’s no attack,’ I assure him. ‘At least, not yet. Would you round up the other Dolphins and bring them to the bridge, please? We’ve got a code to break.’
A few minutes later, Virgil stumbles in, groggy and squinting from working the graveyard shift. Lee-Ann and Halimah follow on his heels. By the time all five of us are together, Jack and I have identified the break where the pattern starts repeating. We have also discovered how to feed the LOCUS’s electrical impulses into the bridge’s speakers, converting the glowing purple squiggles into sounds.
Halimah tilts her head. ‘Blue whale?’
‘Partly,’ I say. ‘But it’s more complicated than that. Keep listening.’
HP has used blue-whale song as a code for years. The pitches, sweeps and lengths of tone can be pegged to components of human languages, making a multilayered form of encryption that is almost impossible to break if you don’t know the key.
But this code is more complicated still.
After a few seconds, the pattern changes. A series of clicks like a dolphin coda overlays the whale song. Two seconds later, the clicks and song are replaced by tones like wind through a conch horn.
Then the pattern repeats.
‘The sender knows HP encryption methods,’ Jack ventures. ‘They must assume we have a LOCUS to receive their transmission.’
‘That’s good, right?’ Lee-Ann says. ‘It must be from our base.’
‘Unless it’s a trap,’ Virgil says. ‘If this is from the Aronnax, and we reply …’
That’s a fun thought.
I find myself shaking my head. ‘No. This must be the base. We were expecting a challenge –’
‘We were?’ asks Halimah.
I tell them about Ester’s warning from last night. ‘So if this is the challenge, and we don’t respond, that will not be good. Either way, we need to decipher the code. Then we can decide what to do.’
My housemates visibly relax. Deciphering a code … that is a challenge we can tackle. It’s what Dolphins train for.
‘Let’s assume the first part is blue whale.’ Jack whips out his pencil and notepad. He starts sketching the purple blobs and waves. He says he thinks better when he’s working by hand, and since he’s our best codebreaker I never argue. ‘That second part, with the clicks … Can we slow that down?’
‘Uh …’ I’m no Cephalopod, but after a few minutes of tinkering, I manage to replay the transmission at one-quarter speed, which makes the pattern clear. ‘That’s five by five.’
I don’t realize Gem is standing behind me until he asks, ‘What’s five by five?’
I almost jump out of my socks. Seriously, I’m going to have to put bells on his holsters so he can’t sneak up on me like that.
‘It’s like Morse code,’ I explain. ‘But different. In the Vietnam War, prisoners of war used it to tap out messages to one another.’
‘And the third section,’ Halimah says. ‘What is that?’
We gather around the map table and play the recording over and over at different speeds. Jack fills his notebook with sketches and mathematical equations. Halimah and Virgil argue about phonetic versus alphabetic symbology. Lee-Ann lectures us on the relationship between acoustics and fluid dynamics. It’s basically a giant Dolphin nerd fest.
I don’t realize how much time has passed until Gem sets a tray of sandwiches in front of us. ‘Lunch.’
While the others eat, I take a bathroom break. I freshen up, splash water on my face, take more medicine. My gut pain is now competing with back pain from being hunched over for so long, looking at codes. I consider throwing up but suppress the impulse by sheer force of will. Once I give in to nausea, the vomit genie is not easy to put back in the bottle.
On the way to the bridge, I freeze in my tracks. Suddenly all the pieces of code that have been swirling around in my brain fall into a perfect pattern. I live for these moments. They’re as exhilarating as cliff-diving, and they’re the main reason I love being a Dolphin. Jack’s a better cryptographer. Halimah is more gifted at navigation. Lee-Ann has a stronger grasp of counterespionage, and Virgil is our expert at electronic communications. But I’m the best at putting all the pieces together to make a bigger picture. That’s why I was elected the freshman prefect.