This story is from The Essential H.P. Lovecraft Collection. The Case of Charles Dexter Ward is about a young man who delved too far into his ancestor's past and paid a frightful price.
Charles Ward was an inquisitive young man. In his research of his family and home town of Providence RI, he found allusions to an infamous ancestor Joseph Curwen. This ancestor's traces had been systematically erased from the public record. Charles should have left well enough alone. Lots of twists in a story written in 1927. Highly recommended.