Open-source alternative to Adobe InDesign

Try out Scribus.

Wikipedia:

Scribus is designed for flexible layout and typesetting and the ability to prepare files for professional quality image setting equipment. It can also create animated and interactive PDF presentations and forms. Example uses include writing small newspapers, brochures, newsletters, posters and books.

You can install it by running:

sudo apt-get install scribus

Also see the question Good Publishing Tool and the thread Open Source InDesign?

Scribus is probably the best alternative to Adobe InDesign right now. Although Inkscape can also do a quite good job. Recently I came across Lucidpress which has a web interface and it seems quite powerful desktop publishing application.

By the way, I maintain a website for open source alternatives to popular software which I update quite frequently. You can check this link for InDesign alternatives:

http://www.opensourcealternative.org/open-source-alternative-indesign/