English Breakfast

"The artist, Geraldinium, has installed an electric kettle and a large teapot..." began the opening sentence of the codebook. Emma, head of the Secure Service, looked up at her codemaster and frowned.
"How is this supposed to work?" she said, raising pencilled-in eyebrows and pushing mousy-brown hair back with a freckled hand. "Do these words all mean something special, and the order they go in then conveys the message?"
"No." The codemaster, who referred to himself as Alpha, shook his head for emphasis. "This is a multi-stage polyalphabetic quasi-Playfair cypher, which we then embed steganographically in artwork, typically that created by Geraldinium Holmes, and export back to the Sisterland. It's not for emergency messages, we use standard quantum cryptographic algorithms and secure channels of communication for that, but for ordinary messages we seek ways of passing them back that aren't even suspected as being such."
"So is this part of the code, or just background information?"
"Both." Alpha smiled thinly, his teeth just visible behind stretched red lips. "Use the first four words to set...." His voice droned on, and at one point he started drawing a geometric diagram on a napkin he must have brought into the office with him. Emma let her eyes rest on him, but she wasn't listening anymore. Hanging above her desk, behind Alpha, was a painting by Geraldinium Holmes entitled "Chihuahua reaching for cake", and Emma dearly wanted to know if there was a hidden message in it now.
"...eighty-eight miles an hour," said Alpha, and stopped talking.
"Right, that's good then," said Emma. She pointed at her painting. "Is that a steganographical message then?"
"You weren't listening," said Alpha reproachfully. His eyes seemed to dull slightly. "I just quoted three minutes of Back to the Future, and you didn't notice."
"Right," said Emma. "But the painting behind you?"
Alpha turned to look at it. "Is just a painting," he said. "Geraldinium does produce some original artworks, you can usually tell them because they're execrable."
"I rather liked it," said Emma, who'd paid for it herself. "Not a coded message then?"
"No," said Alpha. "I could have it checked for you though, but you wouldn't get it back. In one piece."
"Right, that's a no, then, thankyou," said Emma. "Now, tell me again what I'm supposed to do when Geraldinium, in this little story here, discovers that there's no hot water in the kettle because the chihuahua had drunk it all?"