The Cat Who Walks Through Walls

Set in the same universe as The Moon Is a Harsh Mistress, The Cat Who Walks Through Walls is one of Robert Heinlein's later works. It features yet another soldier-of-fortune in the character of Richard Ames, a retired colonel who begins the story living on a cushy space station. His easy life is quickly upended when he marries Gwen Novak, who is secretly a Time Agent, and on a mission to save the universe. Richard and Gwen are chased across the galaxy by unknown enemies, and eventually take refuge in a multiverse paradise, populated by many familiar characters from other Heinlein books, including Jubal Harshaw and the ubiquitous Lazarus Long.

The story operates heavily on the ideas perpetuated in Time Enough for Love and Number of the Beast -- The World As Myth, Heinlein's personal philosophies regarding group marriages and the perils of socialism. It also features one of the most confusing endings of any of Heinlein's novels, leaving two characters stranded and alone and refusing to say whether or not anything was actually achieved. In fact, the resolution to the Cliff Hanger ending is not revealed until the sequel, To Sail Beyond the Sunset.

Provides Examples Of:

 * Achievements in Ignorance: Pixel, the titular cat, can walk through walls and possibly through space-time-universe. At a loss to explain how, the characters theorize that he doesn't realize that he can't.
 * Action Girl: Despite Richard's attempts at machismo, Gwen is a far superior combatant.
 * Almighty Mom: "Auntie" Washington, who springs Richard and Gwen from Hong Kong Luna through sheer force of personality.
 * Apocalyptic Log: The story is written in first person and framed as Richard writing his memoirs. The final Cliff Hanger is written retroactively as Richard dictating to his journal, without revealing to the reader whether.
 * Author Filibuster: Heinlein is (in)famous for this. This book is not quite as bad as others, but there are a few notable instances, particularly when the main character is shouting or sneering at bureaucracy.
 * Author Appeal: All of Heinlein's favorites make an appearance--group marriages, free love, TAANSTAFL, witty (and somewhat sexist) innuendo. This book practically runs on Author Appeal.
 * Bolivian Army Ending: Forms the Cliff Hanger at the end, with the fate of the protagonists left unresolved.
 * Canon Welding: An integral part of The World as Myth concept, this novel brings together heroes from every other timeline Heinlein wrote in the effort to rescue Mycroft Holmes from Luna.
 * Casual Interstellar Travel: The World As Myth has been taken to its logical conclusion in this novel, with the Burroughs device enabling instantaneous travel from any point in space-time-universe to any other, and thereby making war possible on a scale never seen before.
 * Cats Are Magic: Pixel -- see Achievements in Ignorance and Chekhov's Gunman.
 * Chekhov's Gunman: Pixel, the titular cat. He walks not only through walls but also space-time-universe, apparently via not being aware that he can't.
 * The Chessmaster: Lazarus, and Gwen by proxy. Their scheme to manipulate Richard is epic in its scope, and that itself is only a small part of the larger plan which is to rescue Mike Mycroft from Luna.
 * Cliff Hanger: The novel ends on one. To Sail Beyond the Sunset reveals that.
 * Cosmic Retcon: By way of persuading Richard to join his organization, Lazarus arranges for a particular unsavory incident from Richard's past to have never happened. This is of course to demonstrate the power of the Burroughs device to literally rewrite histories on a whim.
 * Divided States of America: Although not discussed in any great detail, this novel is in the same timeline as Friday, where this occurred.
 * Eat the Dog: When passing through Lunar customs, Gwen claims to keep a baby alligator in her purse and declares it to the agent as a pet and possibly food.
 * Every Man Has His Price: Richard and Gwen bribe their way through Luna, where this seems to be standard operating practice. Richard himself appears incorruptible but succumbs to a more indirect form of bribery: having his past rewritten.
 * Extruded Book Product: Richard claims to write pulp romance novels of no literary merit purely to pay his bills. He says he tried writing war novels, but his personal experience made it impossible for him to write stories that readers would accept due to Reality Is Unrealistic.
 * Free-Love Future: On some planets, and most especially Tertius. Richard, who comes from relatively free Luna, is shocked by the level of perceived promiscuity on Tertius, but being a Heinlein character, he quickly adapts.
 * Genius Breeding Act: The Burroughs from The Number of the Beast have by this point in their continuity had a number of children among themselves and with Libby Andy Long, all of whom are indeed supergeniuses.
 * Handicapped Badass: Richard walks with a cane thanks to an artificial foot -- the original was lost in war. On Tertius, he gets a clone graft replacement.
 * Have We Met Yet?: Due to the sheer quantity of overlapping time sequences in the novel, "Are we inverted?" becomes something of a Running Gag.
 * Hitler's Time Travel Exemption Act: Discussed Trope and Deconstructed Trope -- Lazarus' team attempted to assassinate Hitler a few times, but every attempt made things worse in For Want of a Nail fashion. One such timeline ended in nuclear Armageddon and another resulted in the U.S. becoming a fundamentalist theocracy.
 * I Know You Know I Know: Lazarus and his enemies at times seem to be playing this sort of game, in a Sherlock and Moriarty fashion, over who can be more successful at making their manipulations stick. At one point, an entire planet is nova bombed by their adversaries, after which his team of genius mathematicians figures out a scheme to rescue all its people just prior to the event, so that the attack appeared to be successful but nobody was actually lost.
 * It Is Pronounced "Tro-PAY": A rather involved discussion takes place regarding the cultural ramifications of the spelling and pronunciation of the name Tolliver/Talliafero. It turns out to be a Red Herring anyway.
 * Kindhearted Cat Lover: All of the protagonists are this, another Heinlein trademark.
 * Left Hanging: Some of the characters at the end. This is in part to expand on the concept of characters being written by an eternal and possibly ambivalent Author.
 * Love Interest: Gwen gets Richard to marry her in the first chapter, invoking this trope as a means of ensuring that he'll have a reason to do what she wants, while making him think it's all his idea.
 * Massive Multiplayer Crossover: Courtesy of World as Myth, the novel features characters from:
 * Glory Road
 * The Moon Is a Harsh Mistress
 * The Number of the Beast
 * Stranger in A Strange Land
 * Time Enough for Love
 * Monowheel Mayhem: Richard and Gwen are attacked on the Moon by a heavily armed monowheel. It looks anachronistic because it is; it's one of the rival time factions trying to kill him.
 * Most Writers Are Writers: Richard is a writer. He views it as an obnoxious habit, much like smoking, and warns Gwen when she proposes to him that she'll have to deal with him when he gets the itch.
 * No Party Like a Donner Party: Richard has a black stain on his soul -- in a particularly desperate moment, his squad was forced into cannibalism to survive. Lazarus arranges to remove it.
 * Obstructive Bureaucrat: The Manager of the space station where Richard lives evicts him in a passive-aggressive manner by turning off his lights, changing his locks, and refusing to acknowledge that any such was done. Gwen gets even by smearing Limburger cheese on the heating element in the Manager's office.
 * Offscreen Moment of Awesome: The Final Battle against the rival time force is not narrated at all, but recounted via Richard's dictated journal recording,.
 * One Degree of Separation: Thanks to multiversal Time Travel mayhem, it turns out that, and thus comes by his obstreperousness very naturally.
 * One Nation Under Copyright: The Golden Rule space station is run by the Golden Rule Corporation. The Manager is the one and only law, and if you don't pay your air tax, you get Thrown Out the Airlock... or worse.
 * Perspective Flip: In one alternate universe, Albert Einstein is seen as a villain worse than even Adolf Hitler, because he is blamed for the invention of nuclear weapons.
 * Precocious Crush: Gretchen on Luna develops a crush on Richard. She enlists in the Time Corps and ages up in a different timeline, just so she can bundle with Richard when she gets back -- a few months later from his perspective.
 * Privately-Owned Society: The Golden Rule space station, and on Earth, some corporations have gained voting rights.
 * Rage Against the Author: At the end, Richard rails against the kind of Author who would violate Infant Immortality by.
 * Reality Is Unrealistic: Discussed Trope. Richard is a retired colonel and tried writing war novels, but couldn't sell them because he wrote too accurately.
 * Ret-Gone: One of the members of Lazarus' Time Police force is a Lensman. After he in a fit of anger, they arrange to have him removed from existence. The effect is described as like seeing him rubbed out by an invisible eraser, followed immediately by the mortal wound that he inflicted vanishing.
 * Ripple-Effect-Proof Memory: Discussed Trope -- it fades after a while.
 * Shoot the Shaggy Dog: At the end, . Part of Richard's Rage Against the Author has to do with this.
 * Spank the Cutie: Young Gretchen offers to let Richard spank her. He turns her down, telling her to grow up first. Thanks to Time Travel, she does, and reinstates the offer.
 * Staged Shooting: Richard thinks that this has happened and that he's being framed for a fake murder. It turns out later to have been real.
 * Time Police: Lazarus has founded an organization of Multiversal sentinels whose mandate is to protect the integrity of history across multiple universes.
 * Time Travel: The massive overlapping use of this throughout the novel leaves the protagonist hopelessly confused at times, and by proxy, the readers.