" . . . The horrors they encounter are too numerous to list, and you wouldn't want me to even mention the worst of it, which includes mushrooms, a desperate search for something lost, a mechanical monster, a distressing message from a lost friend, and tap dancing."

A SERIES OF UNFORTUNATE EVENTS number eleven begins with the Baudelaire siblings exactly where we left them: In turmoil. As usual. As they sweep down Stricken Stream on a toboggan, they worry about Quigley Quagmire, who fell into the icy water and got swept away by another current, and they ponder other problems: What or where is the Hotel Denouement (at which they are to meet Quigley later); what exactly is V.F.D. and why should they care; and why did Count Olaf care about some elusive sugar bowl? They decide to stay on the toboggan and see where the water cycle takes them, and just hope it keeps them away from Esmé Squalor, Carmelita Spats, and worst of all COUNT OLAF.

Rushing down the stream, they encounter the obvious remains of a fire: The carnival that was burned down in book nine. Soon afterwards, they are almost swept away by a disastrous current, but a submarine arises and stops their progress. They knock, hoping to be let in (by someone who isn't an enemy), and they are asked the famous question: "Friend or foe?" Replying that they are friends and by chance giving the correct password, they are called by their last name and told to enter by an unknown person.

The voice belongs to a man named Captain Widdershins, and he has an unusual way of speaking, throwing "Aye!" and "No!" into every sentence, never failing to complete every thought with an exclamation mark. His personal philosophy is "He (or she) who hesitates is lost!" and he and his stepdaughter Fiona live aboard the submarine Queequeg, wearing uniforms with Herman Melville on the front. Captain Widdershins identifies himself as a friend by claiming that everything the newspaper has accused them of is a lie, and expresses sadness over the death of their kind Aunt Josephine. He announces that Violet can help them by repairing a broken telegram device, Klaus can assist in interpreting tidal charts, and Sunny can help by preparing meals for the crew. (She got a little cooking experience in the last book.) But before they get to work, they are introduced to the submarine's current cook--who turns out to be Phil, one of the few allies they've met along the way (this one from Lucky Smells Lumbermill, in book four). Apparently "The Submarine Q and Its Crew of Two" has had other inhabitants in the past, two of which were Jacques and Lemony Snicket (though Lemony is referred to as "what's-his-name, Jacques's brother"). Captain Widdershins wants the Baudelaires to get to work immediately, and when Fiona suggests they at least get to rest a little, he identifies the time-sensitive mission for this book: Find the sugar bowl before Count Olaf does!

The Baudelaires follow Fiona to get some uniforms. During this process, Fiona reveals that she doesn't know why the sugar bowl is important; her stepfather won't tell her. When the Baudelaires put on their uniforms (featuring Herman Melville), they feel a comforting sensation of finally belonging somewhere for the first time in ages, despite the fact that the uniforms don't really fit any of them exactly (especially Sunny--but after all, they've worn pinstripe suits that fit even less).

Shortly afterwards, there is a terrible sound, which they find out is the submarine slamming into some rocks due to a damaged steering mechanism. Violet offers to try to fix it, but Captain Widdershins insists that she look at the telegram device first, since without it they can't receive "Volunteer Factual Dispatches," which will contain clues on how to find the sugar bowl. The siblings all get to work, and before long it is evening and the captain calls a meeting. They have reached the ocean, he says. Violet announces that the telegram machine wasn't broken in the first place, so the people who were sending them must have had their devices destroyed. Klaus, for his part, hasn't made much progress with the charts, but he does have a conversation with Fiona in which she reveals she is a mycologist, and Captain Widdershins accuses them of flirting. Klaus believes the sugar bowl would have been carried by tidal currents to a place marked "A.A.," which turns out to be Anwhistle Aquatics, a marine research center belonging to their Aunt Josephine's brother-in-law. Well, it had, anyway, before it burned down, like every other place belonging to the good guys in this series. The sugar bowl is supposed to turn at "A.A." and end up at "G.G.," where it could go either direction. The captain doesn't know what "G.G." could be. They decide to set a course for "G.G.," but first, it's time for cod and potato chowder.

Unfortunately (isn't that the name of this series?), dinner is interrupted by a sonar detection believed to be Olaf. They have to power everything down to avoid detection. As his octopus-shaped craft approaches the Queequeg, everyone becomes silent, and they are about to be discovered when another shape shows up on the sonar, shaped like a question mark. Olaf flees at the sight of it, missing his mark. Captain Widdershins claims that the question mark is something even worse than Olaf. Saved for the moment, they begin to prepare for dinner, but then Klaus has an epiphany and realizes he knows where the sugar bowl is, even if he doesn't know why it's important.

Silliness ensues for a while, because the captain's odd way of speaking drops the information that Fiona has a long-lost brother. As a reward for finding the sugar bowl, Captain Widdershins offers to let Klaus marry Fiona, let Violet marry the long-lost brother, and let the whole thing happen in a double wedding aboard the submarine. Ahem.

Klaus says that the sugar bowl was carried inside an underwater cave of some kind, but beyond that, they know nothing--they'll be traveling in uncharted waters. Captain Widdershins gives them some history about V.F.D. explorers and other volunteers who specialized in fish domestication. He mentions that there is actually a third Snicket sibling who's never been mentioned before: Kit Snicket, who helped to build the Queequeg. Anyway, in a mushroom book's table of contents, they find the secret of "G.G."--it stands for Gorgonian Grotto. And this grotto is full of poisonous mushrooms that can kill with their spores.

The mission to go to the Gorgonian Grotto is set, and the captain sends all the children to bed for some rest. They're awoken by the sound of the submarine hitting something again; this time it's been wedged in the conical grotto, unable to go further. The Baudelaires and Fiona must go on in their diving suits, blindly, hoping the current will carry them to the same place it carried the sugar bowl.

In the complete darkness, the four children drift along until strangely enough they hit a beach, though they don't know how or why. It turns out they're on an artificial beach in a research facility, so they take off their helmets and search for the sugar bowl. Though they find a lot of useful and useless objects, there's no sugar bowl . . . but then, unfortunately, Fiona finds the mycelium to the poisonous mushrooms, which surround the children and trap them.

Luckily (for once), the mushrooms don't get close enough to poison the children, but they are forced to sit and wait until the mushrooms recede, which they will do at an unknown time. They pass the time by looking for clues in the junk buried in the sand, and they eat some lo mein Sunny has prepared for them. The kids discover a type of code that the members of V.F.D. sometimes used, making use of fractured poems to communicate messages. They decide to create a code among themselves, using food names, so they can communicate if they end up getting captured. They also discover that Gregor Anwhistle had actually cultivated the poisonous mushrooms to use on the bad guys, which caused ripples with the good guys as to whether that was the right thing to do. They talk about Fiona's brother Fernald and ponder the secrets of the V.F.D. schism.

Soon the fungus begins to wane, which means it is safe to leave. The kids gather up the materials they think will be interesting, and Violet pockets a newspaper clipping that she lies is not important. She doesn't want to talk about it in front of Fiona, but doesn't say why. Apparently Violet does not trust Fiona as much as the younger Baudelaires do. The text reveals at this time that a mushroom spore is in the helmet of one of the Baudelaires, though it does not say which one.

When they get back to the Queequeg, the crew is missing, leaving behind only some balloons marked with the initials "V.F.D." Exploring, they begin to take off their helmets, but Fiona stops Sunny because she notices a little fungal growth on the inside. Sunny has been poisoned, and they must make an antidote or she will die within the hour. They can't even let her out because then the fungus will spread to the others. Fiona appoints herself captain and begins giving orders to the elder Baudelaires, saying she'll do the research to create an antidote herself. And as if this wasn't bad enough, the sonar begins to pick up Count Olaf, who is right on top of them.

Olaf's octopus ship sucks the Queequeg inside, and Olaf captures the Baudelaires and Fiona. Amid much threatening to throw them in the brig, they run into Esmé, who is wearing a "stylish" octopus dress and holding a wet noodle over Snow Scouts who are being forced to row the ship. And then Carmelita comes out, dressed as a tap-dancing ballerina fairy princess veterinarian. She threatens them all with a dance recital. Sunny gets even sicker at the thought. Olaf won't let them go back to their ship to continue a cure for Sunny, as he doesn't care if one of them dies. He only needs one to be alive in order to steal their fortune. Into the brig they go, being promised torture by the hook-handed associate of Olaf's. But the hook-handed man unexpectedly turns out to be Fiona's brother.

They argue about who's on "the wrong side," and admit to each other that people are not good or evil; even good people do some bad things. Fernald agrees to let the orphans go back to their ship if they will take him with them. This they do, and Fiona and her brother distract Carmelita and the crew so the Baudelaires can get away. Klaus reads a mushroom book and finds that the cure is horseradish, but they don't have any. Sunny helpfully points out that wasabi is an alternative to horseradish, and they happened to find a can of that in the assorted junk back in the grotto. They feed it to her and she is cured, and they eat the rest themselves in case they were exposed. The diving helmet remains closed and infected.

The next thing they know, they're receiving a telegram from Quigley Quagmire. They're overjoyed to know he survived--Violet especially--and they eagerly read his message, which of course is coded with the poetry code, saying where to meet him on Tuesday. Remembering how their parents hid off-limits books on the top shelf behind other dull-seeming books, the Baudelaires find that Captain Widdershins did the same, and they find the poetry books they need. Briny Beach is the place to meet--though that's sad because that's where the children were when they found out they had to go live with Count Olaf in book one. Before they can decode the second poem, though, Olaf bursts in and treats them to special laughter, accompanied by Esmé, Carmelita, Fernald, and Fiona--and they are all wearing uniforms decorated with the face of Edgar Guest. However reluctantly, Fiona seems to have joined the other side.

Fiona claims that she's joined Olaf because he's promised to help her find her missing stepfather. While the other villains go off in search of valuables to steal, Fiona is left to "guard" them, which allows them to discuss what's become of their relationship. Fiona wants their family together at all costs, while the Baudelaires claim that Fiona's brother is wicked and she shouldn't try to stay with him. Finally Fiona decides she'll let them escape and make it look like an accident, and the Baudelaires give her the helmet with fungus in it to study (though Olaf thinks it should be used as a weapon). That question-mark shape has appeared on the sonar again, so the villains make a quick escape, but Fiona doesn't put the orphans in the brig. She gives them a fond farewell and actually gives Klaus a good-bye kiss. Left alone, they plot a course to navigate the Queequag out of Olaf's vessel. Sunny patches a damaged porthole with gum, and out they go.

On the way to Briny Beach, they eat Violet's birthday cake, and eventually they open the hatch together and climb out. Waiting for them on the beach is . . . Mr. Poe! He insists they are to go with him, but Violet has decoded the other poem, which reveals they should instead get into a waiting taxi. They deliberately refuse Mr. Poe's instructions and run for the taxi, which is in fact waiting for them. Violet hopes to find Quigley inside, but instead they find Kit Snicket, with two very familiar books of poetry. Here the tale ends . . . for now.

The next volume, The Penultimate Peril, continues their adventures.