This Isn't What It Looks Like is a book by anonymous author Pseudonymous Bosch. It is the fourth book in the pentalogy "The Secret Series", and is the sequel to This Book Is Not Good for You, If You're Reading This, It's Too Late, and The Name of this Book is Secret. The book is based on the sense of sight as the other books are based on scent, sound, and taste. It acts as the continued part of This Book Is Not Good For You, starting just after Cass eats the magic "Time-Travel" chocolate and falls into a coma, searching for her ancestor, the Jester, to find out what the Secret of immortality is, as she recently became the new Secret-Keeper of the Terces Society. Meanwhile, Max-Ernest tries to save Cass with a special monocle, as the book centers around the sense of sight.
One of the most major secrets revealed in the story is that Pseudonymous Bosch may possibly be Max-Ernest, as the later described in the story that he saw his future self writing about him and Cass. As it is unlikely Bosch actually went on the adventures Max-Ernest went on with Cass, it is possible he simply based Max-Ernest on himself as a child. He also tells the story of when he nearly drowned in a jar of mayonnaise, describing how when he was a baby an old pea had gotten stuck in the folds of his thigh, causing him to scream and cry all the time. One day, however, at a restaurant, a waitress takes him to quiet him, discovers the pea, and washes him out in a very large jar of mayonnaise to get it out. However, he sinks to the bottom, and she is unable to get him out. However, the head chef rescues him, and squeezed the pea out of his thigh. Ever since then, Pseudonymous Bosch has had a morbid fear of mayonnaise, and a warm affinity for sous chefs.
Plot The story starts off with Cass awakening somewhere unknown to her, in an unknown time (she later finds she is in fact 500 years in the past), not knowing who she is, where she came from, or what she is doing. She sees a young boy stuck in a tree, and tries to rescue him, only to hear him repeatedly shouting the word "Goat!", evidently frightened. He runs down the road to his father, but neither of them even look at the girl. Confused, the girl walks up to a puddle, only to see that she has no reflection, realizing that she must be invisible, and that the boy was shouting "Ghost," not "Goat."
Meanwhile, Max-Ernest visits Cass in the PICU section of the hospital, where Cass lies in bed comatose. Max-Ernest, though evidently depressed over his friend comatose, (and the fact that the Tuning Fork won't help him create the antidote for Cass) with his only other friend Yo-Yoji away in Japan has overcome his "fear/allergy" of chocolate and eats several bars in a matter of seconds.
Back to Cass, she realizes she has somehow traveled in time and arrived in the Renaissance/Middle Ages. She also realizes she's invisible, not dead. At the streets, she meets a Seer, who can see her because she has something called the "Second Sight", obtained by an object called the Double Monocle (as this book centers around the sense of sight). She also does some fortune telling with a deck of tarot cards with Cass, showing her that the Ace of Wands card is upside down, meaning that an old wrong must be righted. The Seer gives a suggestion that maybe something has been stolen or she has stolen something. She then shows Cass the Fool card, with a picture of a fool, coincidentally the one that she saw while in the streets. When the Seer introduce her name as Clara or Cassandra, Cass's memories came back, making her remember about the Magician, the Jester, the Secret etc. She realizes she's on a mission to find the Secret, since she is the new Terces Society Secret Keeper. The Seer disappears but leaves Cass the Double Monocle.
Meanwhile, Max-Ernest goes to visit Pietro, who is playing Tarocchino with the circus crew. Pietro introduces the idea of tarot cards that has involvement in Cass's coma, which confuses Max-Ernest. Pietro explains that the Ace of Wands card is upside down, which refers to the fact that the Tuning Fork should be returned to their principal, Mrs. Johnson. He explains the Fork wants to be returned to its owner, so that is why it won't work. Lastly, Pietro tells Max-Ernest that he "must bring her home from her head" with mind reading.
Back to Cass, she experiments with the Double Monocle, which she finds out that she could see through walls. When a parade comes to the streets announcing that the Duke is to give gifts of riches to the King, Cass, taking advantage of her invisibility climbs onto the parade, believing that it'll lead her to the palace, where she could find the Jester. The parade is raided by Anastasia and her bandits, who returns the jewels and riches to the poor. She also discovers a lodestone that attracts a lot of metal which she keeps. Back at school, when Max-Ernest is about to return the Tuning Fork to Mrs. Johnson, he meets the new secretary Opal, who pranks him into not knocking on Mrs. Johnson's door, resulting in her scolding him. The principal is dressed like a queen, because of the upcoming Ren-Faire, a Renaissance themed fair. Max-Ernest sees that Mrs. Johnson is wearing the lodestone as a necklace, who she explains that her great great aunt Clara was wearing it. At the palace, Cass sees a man telling a creature to sleep in the dog kennels. The creature is Mr. Cabbage Face. When she calls out his name, the homunculus looks at her, meaning that he could see Cass. Cass realizes if Mr. Cabbage Face is here, then Lord Pharaoh, the founder of the Midnight Sun (evil alchemists who go murderous lengths to seek immortality) is too. Cass also realizes that in the Tale of Mr. Cabbage Face, the author got the place where the homunculus stayed in the palace wrong. It wasn't a pigsty, but a dog kennel.
Meanwhile, Benjamin Blake arrives from his old school, the New Promethean, completely changed. He is now wearing a tuxedo and owns the Double Monocle. He eats lunch with Max-Ernest, Daniel-not-Danielle and Glob in the Nuts Table. Benjamin reveals a note stuck on Max-Ernest's back, saying a strange message. At the kennels, Cass talks with the homunculus after giving him some leftover chicken as he was starving. When Cass gets the homunculus to speak a bit, the Jester arrives and carries own the conversation as notated in The Tale of Cabbage Face: A Gothic Tale. The Jester frees the homunculus before he is caught and sent to the dungeon, which is the place where the chamber pots are emptied. At Max-Ernest's house, Max-Ernest's parents announce that they are expecting a baby boy, overwhelming Max-Ernest.
At the dungeon, Lord Pharaoh suddenly arrives and bumps into an invisible Cass, causing the Double Monocle to fall off. Lord Pharaoh uses it and realizes the presence of Cass. Lord Pharaoh confiscates all of Cass's belongings (just a triangle of Senor Hugo's chocolate which he took to investigate) and throws Cass into a cell with the Jester. Cass reveals to the Jester that she is invisible and is his great great granddaughter. He first disregards it as madness but slowly believes her. At school, Max-Ernest decodes the message and reveals a troubling "LORD PHARAOH LIVES" (probably because Lord Pharaoh ate Cass's chocolate). At school, Amber invited Max-Ernest for a fortune telling session and when telling him that he is in love with Cass, Benjamin reads her mind and reveals to everyone that she lied, breaking her reputation. Benjamin reveals to Max-Ernest that he can mind read and agrees to read Cass's mind, like Pietro said. Max-Ernest would have to act an injury while Benjamin sneaks in.
Meanwhile, Anastasia frees everyone in the dungeon and flees to her campsite. At the hospital, the janitor notices Cass whispering "The Secret....what is the Secret..." but decides not to report it immediately. Then, Max-Ernest charges into the Emergency Room screaming because he has an "epileptic fit with the combined result of his allergy to vinyl and a cardiac arrest with the effects of white coat syndrome". But Max-Ernest's cover is blown, resulting in him to go back to Cass's room, just as Benjamin was about to see something. At home, Max-Ernest receives an Email from Yo-Yoji telling him that the school Benjamin went to is run by the Midnight Sun, Dr. L being principal. Max-Ernest sees why Benjamin was so eager to find out what was in Cass's mind. At the campsite, the bandits are ambushed by the soldiers. At school, Max-Ernest eavesdrop Benjamin and Amber talking. Amber was begging Benjamin to let her try the monocle. Eventually she lunges and grabs Benjamin's monocle, and sees through walls and almost catches Max-Ernest. Max-Ernest discovers that Benjamin has no mind reading powers, it's just his monocle. Benjamin tries to get the monocle back but Max-Ernest runs with it. He trips and Opal catches the monocle and reports Benjamin and Amber to the principal and sends Max-Ernest to the nurse's office. Opal leaves her purse there, giving Max-Ernest the chance to get the monocle. At the campsite, the other soldiers and their dogs search for Cass. The homunculus saves her by letting the dogs chase him. He also leaves Cass the treasure chest. In the treasure chest, Cass finds the lodestone and the Jester and Cass save them by throwing the a sword onto the lodestone the Jester uses it to play a trick where Cass throws a sword, instantly attracted to the magnet and making the soldiers beg for forgiveness, as they thought something supernatural had occurred. At the hospital, Max-Ernest could not find Cass as she has left the hospital because there is nothing the doctors could do. Max-Ernest uses the monocle to see himself in the mirror, revealing his future self eating massive amounts of chocolate and writing a book. It seems as if Pseudonymous Bosch is Max-Ernest because of his love of chocolate and being a writer.