The Cat Who Walks Through Walls by Robert A. Heinlein

A Comedy of Manners

In this science fiction novel, a former military officer and writer named Richard Ames becomes embroiled in a complex and dangerous adventure after a mysterious woman named Gwen asks for his help. The story unfolds across various settings, including a space habitat and a lunar colony, as Richard and Gwen navigate a web of intrigue involving time travel, political conspiracies, and interdimensional travel. As they encounter a diverse cast of characters, they must unravel the mystery surrounding a secretive organization and a legendary figure known as Lazarus Long, all while facing threats to their lives and the stability of their universe.