Complex sentence: The nearby Hawkins National Laboratory ostensibly performs scientific research for the US Department of Energy, but secretly does experiments into the paranormal and supernatural, including those that involve human test subjects, which start to affect the unknowing residents of Hawkins in calamitous ways.
Split into simpler sentences: The nearby Hawkins National Laboratory ostensibly performs scientific research for the US Department of Energy, but secretly does experiments into the paranormal and supernatural, including those that involve human test subjects. These start to affect the unknowing residents of Hawkins in calamitous ways.