Complex sentence: The Hedgehog in the Cage (in Czech: Ježek v kleci) is a mechanical puzzle popular in the Czech Republic which features prominently in the "Dobrodružství v temných uličkách" (Adventures in the Dark Alleys) trilogy of adventure stories by Jaroslav Foglar.
Split into simpler sentences: The Hedgehog in the Cage (in Czech: Ježek v kleci) is a mechanical puzzle popular in the Czech Republic. It plays an important role in the adventure book trilogy "Dobrodružství v temných uličkách" (Adventures in the Dark Alleys), written by Jaroslav Foglar.