Inversions is a science fiction novel by Scottish writer Iain M. Banks, first published in 1998. Banks has said "Inversions was an attempt to write a Culture novel that wasn't."

The book takes place on a fictional planet resembling Europe during the Late Middle Ages. A large empire broke up in the decade or so preceding the action, apparently from meteor or asteroid strikes that severely affected farming across much of the globe. The remnants of the empire still war with one another.

The narrative alternates chapter-by-chapter between two concurrent story-lines, with alternating chapter headings of The Doctor and The Bodyguard.

The first storyline is presented as a written account from Oelph, publicly a doctor's assistant, but privately a spy for an individual identified only as "Master", to whom much of the account is addressed. Oelph is the assistant to Vosill, the personal doctor to King Quience of Haspidus—and a woman. The latter is unheard of in the patriarchal kingdom, and is tolerated only because Vosill claims citizenship in the far-off country of Drezen. The King himself is appreciative of her and her talents, but nonetheless her elevated position in defiance of the kingdom's social mores inspires hostility among others of the court.

Oelph's account follows Vosill as she attends to the King regularly, as well as more charitable ministrations to the impoverished and those in need. Her methods are unconventional by kingdom standards, for example forgoing the use of leeches and instead using alcohol to "kill the ill humours which can infect a wound," but are more often than not successful. This only serves to inspire more distrust amongst her detractors, notably including a number of Dukes as well as the King's Guard Commander, Adlain. On this topic, Oelph includes a transcript he claims to have found in Vosill's journal, purported to be an exchange between Duke Walen and Adlain in which they make an agreement, "should it become necessary", to covertly kidnap the lady doctor and have Nolieti, the King's chief torturer, "put her to the question." Oelph notes that while the transcript appears to have been obtained under impossible circumstances, he somehow does not doubt its veracity.

While Vosill attends to the King, Nolieti is murdered, nearly decapitated, presumably by his assistant Unoure. Vosill examines the body and determines that Unoure could not have killed his master, but her explanation is disregarded. Unoure is captured, but before he can be questioned he is found in his cell dead from a cut throat, apparently self-inflicted. Following this account Oelph includes another found transcript, this time between Walen and Duke Quettil, though Walen is unable to obtain Quettil's agreement for the use of Ralinge, his own chief torturer, in Walen's kidnapping plan. Some days later at a masked ball Walen is found murdered, this time by a stab to the heart. The Duke's murder disquiets much of the royal house, as it occurred in a room no one entered or left.

Resentment towards Vosill continues to build, particularly after King Quience begins implementing somewhat radical reforms, such as permitting commoners to own farmland without the oversight of a noble and the creation of city councils, reforms which Vosill has discussed with the King publicly and at length. Following these reforms Vosill confesses to the King that she loves him, a sentiment he rebuffs, and further informs her that he prefers "pretty, dainty, delicate women who [have] no brains." Oelph finds her after this, drunk, and hints at his own feelings of love towards her; she rebuffs him as well, in what might be considered a more gentle way.

Some days later Vosill receives a note from Adlain, asking her to meet him and two other Dukes elsewhere in the castle. She leaves alone, but Oelph opts to follow her in secret; after catching a glimpse of someone fleeing, he arrives in time to be arrested by the guard, who proceed to discover Vosill standing over the body of a murdered Duke, stabbed with one of her scalpels. Vosill and Oelph are almost immediately delivered to Ralinge, who binds the two separately and then strips, intending to rape Vosill. The woman issues what sounds to Oelph like commands, albeit in a language he does not recognize even partially. Oelph's eyes are closed at this point, and in his narrative he is unable to adequately describe what he hears next, other than an impression of wind and metal. When he opens his eyes he finds Ralinge and his assistants dead, dispatched bloodily, and Vosill free and in the process of removing her bindings, no indication of how she was freed. Later, she claims that Oelph fell unconscious and the three men fought over who would rape her first, though she indicates to him that this is what he "should" remember.