The Penultimate Peril is the twelfth installment in American author Lemony Snicket’s
A Series of Unfortunate Events, comprising thirteen books in total.
As the novel opens, it picks up exactly where the previous one left off; the Baudelaire children are in the back seat of Kit Snicket’s taxi. She tells them that she used to work with their parents, now deceased, although to the children she is a stranger. Kit is pregnant and clearly distraught as she drives the children to the Hotel Denouement for their first mission for the V.F.D. The hotel is designed like a giant library, with rooms cataloged by the Dewey Decimal System. The Baudelaires are expected to serve and help the hotel guests.
She drops them off, leaving them with concierge uniforms to use as a disguise, and instructs them to send her a signal that is visible from the sky should their meeting on Thursday be canceled. She also leaves them with a warning, to be wary of the hotel managers. Frank and Ernest are identical twins, and while Frank is a volunteer and all-around good person, Ernest is a villain. The goal of their undercover mission is to figure out which of the guests are working with the V.F.D. They are also hoping to figure out the true identity of J.S. as well as the location of the sugar bowl, an important artifact for the V.F.D. as well as its enemies.
The meeting Kit refers to is one which all of the members of the V.F.D. are expected to attend. Before their arrival, the children are supposed to investigate the hotel to ensure that it is still a safe place to hold the meeting. If they discover that the safety of the hotel has been compromised, they are to send a signal to Kit to warn them so that they are not caught off-guard.
The children are warned that no one can tell the Denouement brothers apart, in spite of their vastly different temperaments. It is of the utmost importance that the children keep their identities a secret so that the enemies hunting them, namely Count Olaf, do not discover them.
On their first day at the hotel, the children spot a remarkable number of villains roaming the property, the cast including various characters from previous books in the series. The children take detailed notes to keep track of whom they have seen and to decipher who can be trusted and who cannot. They are also busy running strange errands assigned to them by the hotel managers. They try to figure out whether the errands are for the benefit of the V.F.D. or their enemies. The tasks include covering the rooftop in sticky bird and locking a Vernacularly Fastening Door in the laundry room.
The Baudelaries soon discover that there is a third hotel manager, Dewey Denouement—the identical twins are actually triplets. Dewey has organized all of the V.F.D.'s information about the villains and plans to present this information at the upcoming trial, which is the purpose of Thursday’s meeting. Count Olaf suddenly appears, threatening Dewey with a harpoon gun and demanding the code for unlocking the Vernacularly Fastened Door, where he is sure the sugar bowl is being held. As they attempt to deter Count Olaf and rescue Dewey, the Baudelaire children accidentally fire Olaf's harpoon gun. Dewey is shot and dies shortly thereafter.
The Baudelaires are put on trial for murder the next morning, brought to the lobby by Frank and Ernest themselves. They stand in front of the judges, blindfolded in order to respect the concept of justice being blind. They are given the opportunity to tell their side of the story, but find themselves having a hard time doing so. Violet starts from Briny Beach where they heard that their parents have perished in the fire. However, the Baudelaires soon realize that the judge, supposedly called Justice Strauss, is none other than the Man With A Beard But No Hair, one of Olaf’s henchmen. The children are accused of being in contempt of the court, and Sunny encourages the other Baudelaires to remove their blindfolds.
The trial cannot be completed as Count Olaf kidnaps the judge to use as a hostage to demand that the Vernacularly Fastened Door be opened. Down in the laundry room, the Baudelaire children unexpectedly decide to help Count Olaf escape the hotel because they know he won't be able to find the sugar bowl, and they will be able to escape beside him. Sunny sets the Hotel Denouement on fire, sending a sign to the V.F.D. that the building is no longer safe for their Thursday meeting. At the close of the novel, the children find themselves adrift in a boat beside Count Olaf.