bolthole

noun3

1. •
   A hole in an animal’s den, or through a wall or fence, used for escape or emergency exit, i.e., a hole the animal may bolt through.

   • Eragon: They may try to slip past us and escape Helgrind through the entrance we used. Saphira: They probably have a bolt-hole at ground level. — 2008
2. •
   (figurative) A hidden place of emergency refuge.
3. •
   (figurative) A second home, etc., where one can seek an escape or refuge from the stresses of everyday life.

   • In the 1950s, Hollywood decamped to the desert – bankrolling the world’s most daring modernist architects to create ever more experimental boltholes. — 2016