After Martha reveals that the words are about secret agents, she is seen playing fetch with Helen in the backyard while a bored T.D. watches. Martha grows bored too, so she suggests they do something "adventurous". Helen is about to say that you can't expect adventure to come to you, but then a car pulls up. A man and a woman, both wearing suits, come out and walk up and hand an envelope to Martha, then drive off. Helen reads the letter, and it says, "Have you ever thought about becoming a secret agent?". The kids think it would be cool if Martha was a secret agent, and give her to the address.
She goes there (to a garage) and asks for "the chief", who doesn't recognise her at first, but realises who she is when she introduces herself as "Martha the talking dog". He explains that he recruited her in an attempt to stop the theft of Granny Flo's soup recipe. Martha imagines to a casino and nearly dodging being poisoned, then in the car, she wonders what her disguise will be. The chief tells her she doesn't need a disguise.
The chief and Martha talk to Granny Flo, who reveals that she keeps the formula in a safe. The chief convinces Granny Flo to hire Martha as a guard dog, alongside a growly dog, who turns out to be another agent — "K9-001". He claims that nothing suspicious has happened, but that might change that night, so the chief tells Martha to watch for anything suspicious once night falls.
She sees someone in the factory, but it's just T.D. As it turns out, he and O.G. tour the factory at night on a regular basis. T.D. offers to help Martha keep watch, and she agrees to it. They spy on a janitor, who enters Granny Flo's office with a flashlight, and so Martha and T.D. come running to O.G. believing the janitor to be the spy.
She tells the chief, who phones Granny Flo, but she doesn't believe the janitor could be the thief. She checks, and the formula is still in its safe, so the chief wonders if Martha fell asleep and dreamt she saw the janitor. However, Martha is still suspicious, so she goes back to the factory. There, she sees the janitor and is intercepted by K9-001, who tells her to deliver a coded message to the chief: "November 29 X".
The chief thanks Martha for giving him all the necessary information, then Martha goes home and tells Helen and T.D. However, O.G. then walks up and reveals the factory is closed due to the formula being stolen, and a dog is said to have helped the thief. To be continued.
Part two begins with O.G. finishing his explanation, and then Martha showing the Kennelly men and Helen to the secret hideout. However, the chief's office is empty (of both people and furniture), and the manager claims there was never a spy agency there. When Martha explains about the coded message, Helen surmises that K9-001 saw the combination for Granny Flo's safe and pretended that was his coded message (since "November" is the eleventh month and "X" is the twenty-fourth letter).
The janitor arrives and reveals him to be an undercover agent named Agent Johnson, who has actually been trying to stop the criminals. On the way home and at home, Martha feels guilty about having helped the criminals. That night, Agent Johnson phones Martha, saying that he has a plan to get the formula back, but needs Martha's help.
Martha meets with Johnson, who introduces her to the scientist who sometimes introduces episodes, who is referred to as "the Professor". The Professor reveals that the chief's real name is Dr. Filthmarker and he lives in an invisible zeppelin, and they need her to smell it. They then disguise her as a pink poodle and send her through the air with a propeller.
She finds the dirigible, breaks in, and is picked up on camera by Dr. Filthmarker and K9-001, whose name, as it turns out, is Bruno. Dr. Filthmarker and Bruno follow Martha's pawprints (since she used orange paint to help find the blimp) and try to grab her by the tail, but it turns out that Martha has slipped out of her poodle suit and freed Granny Flo (who was trapped in a dome). Martha lets Granny use the propeller backpack she used to escape, while she (Martha) distracts the villains.
She spots the formula and eats it, then tells Dr. Filthmarker that he's defeated. However, Filthmarker uses knockout gas on Martha and locks her in a giant hourglass with fleas instead of sand. Then, he initiates the self-destruct sequence and he and Bruno escape with parachutes. Martha breaks out of the hourglass using a diamond on her collar, and is then rescued by Granny Flo wearing the propeller.
She takes her to the bad guys, who are dangling from a tree near the Come On Inn, and they have them arrested. Then, it turns out to have been All Just a Dream. However, it's subsequently revealed that Martha may have dreamt up the events of this part, but the events of part one were real. She figures something out and then has the villains arrested for real. As it turns out, she found out by realising that Bruno's breath smelled exactly the same as the Come On Inn sausages, and therefore the crooks must have hidden at the Come On Inn.
This episode provides examples of
- All Just a Dream: While part one was real, part two turns out to have been mostly Martha's dream. However, the dream does help her solve the real mystery.
- Angry Guard Dog: K9-001 is hired as a guard dog for Granny Flo's safe, and he growls intimidatingly when we first see him.
- Arbitrary Skepticism: Martha can talk, but T.D. can't believe she'd be able to have a doghouse that doubles as a car.
- Astonishingly Appropriate Interruption:
- Martha says, "The chief was actually..." and then the janitor finishes, "...the soup thief."
- When Dr. Filthmarker gives Martha the fake bone, she says, "I'm not in the mood for..." and then when the gas is released, she finishes, "...sleeping gas".
- Bad People Abuse Animals:
- Subverted. Martha appears to narrowly escape being given a poisoned glass of (toilet) water, but it turns out to be in her imagination.
- Downplayed, then later played straight for Dr. Filthmarker towards Martha, when he locks her in an hourglass filling with fleas, which is annoying but not too harmful... but then presses the self-destruct button on his blimp.
- Bald of Evil: Dr. Filthmarker is bald and he's the leader of a criminal gang.
- Barefoot Cartoon Animal: Martha is seen in her imagination wearing a diving suit with no flippers.
- Chekhov's Gun: When Martha first meets Bruno, she notes his breath smells of sausages. At the end, she remembers that the smell matches those served at the Come On Inn, leading to his and Dr. Filthmarker's arrest.
- Comically Missing the Point: Dr. Filthmarker tells Martha to "have a seat", even though she's already sitting.
- Crazy-Prepared: Dr. Filthmarker prepares slides for everything, even the definitions of words.
- Damsel in Distress: Dr. Filthmarker holds Granny Flo captive in a glass dome, then later he holds Martha captive in an hourglass filled with fleas while the dirigible is about to explode.
- Damsel out of Distress: Downplayed. Martha is trapped in a flea-filled hourglass on a self-destructing blimp, but then she breaks out with her diamond-encrusted collar. However, she still needs Granny Flo to rescue her from the zeppelin.
- Daydream Surprise: It appears as though Martha almost gets poisoned at a casino, but then it turns out to all be in her head.
- Evil All Along: Dr. Filthmarker and K9-001 seem like they're trying to stop the formula from being stolen, but they turn out to be stealing it themselves.
- Evil Laugh: Dr. Filthmarker laughs loudly when boasting about his plan working, then again when he puts Martha in the hourglass.
- "Eureka!" Moment: Martha realises that the crooks must have been hiding in the Come On Inn after dreaming about the smell of their sausages, and realising that she smelled the exact same smell on Bruno's breath earlier.
- Fantasy Sequence: T.D. has a daydream sequence of Martha as a secret agent after reading the letter.
- Greed: Granny Flo doesn't want to pay for the guard dog.
- Heroic Dog: Martha saves Granny Flo after the latter is kidnapped.
- Half-Dressed Cartoon Animal: Martha in her imagination wears a suit jacket but no pants.
- Hold the Unsolicited Ingredient: Exaggerated in Martha's imagination, when she orders a drink but "hold the poison".
- Irony:
- Despite liking to be prepared and being Crazy-Prepared when it comes to the slides, Dr. Filthmarker didn't foresee his slide projector breaking.
- Not only was Agent Johnson not actually the thief, he was trying to stop the thieves.
- Insistent Terminology: T.D. says, "You're doing surveillance?", and Martha replies, "No, I'm watching the factory".
- It's Probably Nothing: Dr. Filthmarker sees Martha in her propeller on his radar, but since she's too small to be a plane, dismisses the reading as "nothing".
- I've Heard of That — What Is It?:
- Martha is horrified at the idea of someone stealing the formula for Granny's soup, but then realises that she doesn't know what a formula is.
- She then thinks an "invisible dirigible" is very clever... before realising that she doesn't know what a dirigible is.
- Leaning on the Fourth Wall: Martha complains, "I hate it when it all turns out to be a dream" after waking up.
- Mistaken for Thief: Martha and T.D. see a janitor enter Granny's office with a flashlight and think he's the soup thief, but it turns out that he's a spy tracking down the real soup thief.
- Morally Ambiguous Doctorate: The main antagonist of the episode is Dr. Filthmarker.
- My God, What Have I Done?: Martha feels very guilty about accidentally having helped the soup thieves.
- Mystery Episode: Downplayed. Part one concerns Martha trying to figure out who the formula thief is, and part two concerns trying to stop the thieves.
- Names To Run Away From Very Fast: The main villain is named Dr. Filthmarker.
- Pun:
- Martha's codename begins with "K9", which is a pun on "canine", the scientific name for a dog.
- When Dr. Filthmarker and Bruno are hanging from a tree by their parachutes outside the Come On Inn, Martha says, "Looks like those two decided that the Come On Inn was a nice place to hang out!".
- Riddle for the Ages: Since the janitor turning out to be Agent Johnson was just part of Martha's dream, we never find out why he had a flashlight. He was probably just a normal janitor that was just using unconventional tools, but he may have indeed been a spy just like Martha dreamt.
- Right for the Wrong Reasons: Martha and T.D. were right that Agent Johnson was a spy, but wrong when they thought he was stealing the soup formula.
- Shout-Out:
- Martha introduces herself in her imagination as "Martha. Plain Martha", and she says she prefers her toilet water "shaken, not stirred", which references things said in the James Bond movies. Also a reference to James Bond is her ID "002", which references Bond's "007".
- Martha claims to love the smell of sausages in the morning, which is a reference to the line "I love the smell of Napalm in the morning" from Apocalypse Now.
- Speak in Unison: When Martha sees T.D., they say, "What are you doing in here?!" at once.
- Split-Screen Phone Call: When Dr. Filthmarker phones Granny Flo, they're seen on a split screen.
- Stock Animal Diet:
- K9-001's breath smells of sausages, then Martha says she loves the smell of sausages in the morning. Exploited when Martha finds out that the sausages on Bruno's breath smell the same as the Come On Inn sausages.
- The sleeping gas dispenser is shaped like a bone.
- Sudden Downer Ending: Part one ends with the case seemingly closed... only for the formula to turn out to have been stolen after all.
- Surprise Party: Discussed when T.D. wonders if Martha's letter is an invitation to a surprise party.
- Talking in Your Sleep: According to Helen, Martha talked in her sleep during her dream.
- Tempting Fate: Helen says that adventures don't just come to you, seconds before the suits show up.
- Toilet-Drinking Dog Gag: A waitress serves Martha toilet water.
- Unwitting Instigator of Doom: Martha accidentally gives Dr. Filthmarker, who is one of the formula thieves, the combination for Granny's locker because K9-001 tricked her.
