How can I extract latest topics across all forums inside a category page

I have a category page which has 4 sub-forums inside.

I want to pull all the latest topic inside my custom component, just the way lithium component does (Latest Topic Component)

I dont see direct URL which does that for us

something like http://community.lithium.com/community-name/restapi/vc/categories/id/[id] /boards

But it ask for board id further to pull all the threads inside that board, what i am looking for is if i have multiple boards inside a category i want to pull all the latest threads inside that category with one API call.

Please help.