Tranquility is a package for pushing streams to Druid in real-time. Druid does not come bundled with Tranquility; it is available as a separate download.
Note that as of this writing, the latest available version of Tranquility is built against the rather old Druid 0.9.2 release. It will still work with the latest Druid servers, but not all features and functionality will be available due to limitations of older Druid APIs on the Tranquility side.
For more details, check out the Tranquility GitHub page.