The Wide Window is the third installment of The Series of Unfortunate Events. Like all the books in the series, it focuses on the three Baudelaire orphans (Violet, Klaus, and Sunny) and their attempts to stay out of the evil Count Olaf's clutches. This particular story is of the Baudelaires' time with their Aunt Josephine, who lives in a house on the edge of a cliff above Lake Lachrymose. Josephine has a passion for grammar, but fears pretty much everything else in existence. When the Baudelaires accompany their aunt into town in order to prepare for the oncoming hurricane, they meet a sailor named Captain Sham; the Baudelaires immediately recognize him as Count Olaf, but his disguise fools Aunt Josephine as he flirts with her.
That night, the Baudelaires hear a loud crash and arrive in Josephine's library to see that the wide window in there has been smashed, seemingly by Josephine as she threw herself out the window based on the suicide note she left behind. However, the Baudelaires are suspicious because not only had Josephine taken a call in private from Captain Sham immediately before her death, but her suicide note was full of typos, which they knew she would never do.
But the note says that Captain Sham is their new guardian, so Mr. Poe (the children's incredibly oblivious lawyer) says they have to respect Josephine's last wishes. They meet Captain Sham in town and he offers to take the Baudelaires and Mr. Poe to lunch. In an effort to escape, the Baudelaires eat peppermints, which they are highly allergic to, and when their hives and rashes start to grow, Mr. Poe excuses them to return to Josephine's house.
Once they are there, Klaus realizes that the typos in the suicide note are a clue that leads them to a cave off the lake. After narrowly escaping the collapse of Josephine's house into the lake thanks to a bolt of lightning from the hurricane, the Baudelaires head down to the dock, but the ferry is closed because of the storm, so they decide to take one of Captain Sham's boats. After another narrow escape from one of Count Olaf's henchmen, the Baudelaires sail out to the cave, where they find Aunt Josephine, alive and well.
They convince her to return to town with them, but as they are sailing away from the cave, the leeches that live in the lake attack them. Violet makes a signal, which attracts the attention of the only other sailor on the lake, which just so happens to be Captain Sham. He allows them to come onto his boat, but then pushes Josephine into the water, where she is eaten by the leeches.
When they reach the dock again, Mr. Poe is there, preparing to hand them over to Captain Sham. Before Mr. Poe can do that, however, Sunny bites the wooden leg of Captain Sham, which cracks it in half to reveal that there is a real leg beneath it and it has Olaf's unique tattoo of an eye on his ankle. Unfortunately, Count Olaf escapes before the authorities can be alerted and the Baudelaires are left alone with Mr. Poe, who will take them to their next unfortunate guardian.