The Cat Who Walks Through Walls

Heinlein">Robert A. Heinlein, published in 1985. Like many of his later novels, it features Lazarus Long and Jubal Harshaw as supporting characters.

The Cat Who Walks Through Walls

Author	Robert A. Heinlein
Cover artist	Michael Whelan
Country	United States
Language	English
Genre	Science fiction
Publisher	Putnam Publishing Group
Publication date	1985
Media type	Print (Paperback)
ISBN	0-399-13103-5
OCLC	82423089
Dewey Decimal	813.54 19
LC Class	PS3515.E288 C3 1985
Followed by	To Sail Beyond the Sunset

A writer seated at the best restaurant of the space habitat "Golden Rule" is approached by a man who urges him that "Tolliver must die" and is himself shot before the writer's eyes. The writer—Colonel Colin Campbell, living under a number of aliases including his pen name "Richard Ames"—is joined by a beautiful and sophisticated lady, Gwendolyn Novak, who helps him flee to Luna with a bonsai maple and a would-be murderer ("Bill"). After escaping to the Moon, Gwen claims to have been present during the revolt described in The Moon Is a Harsh Mistress.

Still pursued by assassins, Campbell and Novak are rescued by an organization known as the Time Corps under the leadership of Lazarus Long. After giving Campbell a new foot to replace one lost in combat years before, the Time Corps attempts to recruit Campbell for a special mission. Accepting only on Gwen's account, Campbell agrees to assist a team to retrieve the decommissioned Mike, a sentient computer introduced in The Moon Is a Harsh Mistress. Engaged in frequent time-travel, the Time Corps has been responsible for changing various events in the past, creating an alternate universe with every time-line they disrupt. Mike's assistance is needed in order to accurately predict the conditions and following events in each of the new universes created. Campbell's frequent would-be assassins are revealed to be members of contemporary agencies also engaged in time manipulation who, for unknown reasons, do not want to see Mike rescued by the Time Corps.

During the mission, Gwen is grievously wounded and Campbell loses his foot again, though the Time Corps succeed in retrieving Mike. The story ends with Campbell talking into a recorder (presumably the source of the first-person narrative) reflecting on the mission and his relationship with Gwen.

The Cat Who Walks Through Walls may be regarded as part of Heinlein's multiverse series, or as a sequel to both The Number of the Beast^: 145 and The Moon Is a Harsh Mistress. During a meeting of the Council of the Time Scouts, representatives from every major time line and setting written by Heinlein appear, including Glory Road and Starship Troopers, and references are made to other authors' works as well.

The title of the book refers to a cat by the name of Pixel, who has an inexplicable tendency to be wherever the narrator happens to be (see Schrödinger's cat). In one scene Pixel does, in fact, walk through a wall, and it is explained that Pixel is too young to know that such behavior is impossible.

Gwen Novak is eventually revealed to be Hazel Stone, a character previously featured in Heinlein's The Rolling Stones and who had played a small but important role in The Moon Is a Harsh Mistress. Campbell is also eventually revealed to be a son of Lazarus Long, a Heinlein character originally introduced in Methuselah's Children and who reappeared in Time Enough for Love, The Number of the Beast, and To Sail Beyond the Sunset. Also appearing are Jubal Harshaw, a major character in Stranger in a Strange Land; Galahad, of Time Enough for Love; and Manuel Garcia O'Kelly Davis, the first-person protagonist of The Moon Is a Harsh Mistress.

Dave Langford reviewed The Cat Who Walks Through Walls for White Dwarf #76, and stated that "I'm afraid it's Heinlein self-indulgence time again. What's on the menu is those blasted inter-universal travellers from Number of the Beast, plus walk-ons from Time Enough for Love, Glory Road, The Moon is a Harsh Mistress, Stranger in a Strange Land and more."

• Review by Dan Chow (1985) in Locus, #298 November 1985
• Review by Don D'Ammassa (1985) in Science Fiction Chronicle, #75 December 1985
• Review by Michael M. Levy (1985) in Fantasy Review, December 1985
• Review by Spider Robinson (1985) in Analog Science Fiction/Science Fact, Mid-December 1985
• Review by Fernando Q. Gouvêa (1986) in Science Fiction Review, Spring 1986
• Review by Algis Budrys (1986) in The Magazine of Fantasy & Science Fiction, February 1986
• Review by Baird Searles (1986) in Isaac Asimov's Science Fiction Magazine, March 1986
• Review by Thomas A. Easton [as by Tom Easton] (1986) in Analog Science Fiction/Science Fact, March 1986
• Review by Robert Coulson (1986) in Amazing Stories, March 1986
• Review by Yvonne Rousseau (1986) in Australian Science Fiction Review, #2, May 1986
• Review by Nik Morton (1986) in Vector 132
• Review by John Clute (1986) in Interzone, #16 Summer 1986
• Review by Brian Stableford (1986) in Foundation, #36 Summer 1986
• Review by Paul Fernandez (1987) in Paperback Inferno, #64