Index updated with information from Tom Lammers and atlastales.com.
Possible Sekowsky pencils per Michael J. Vassallo. Possible Becker pencils per Jim Vadeboncoeur, Jr.
Semi-historical account of the Molly Maguires, a secret Irish immigrant labor organization in the coal mining districts of Pennsylvania, and the efforts of Pinkerton Agency undercover detective James McParlan (1843-1919) to break up the group in 1873-76; detective agency founder Allan Pinkerton (1819-1884) appears.
According to The Invincible Gene Colan by Dr. Michael J. Vassallo (Marvel, 2009), this story was pencilled by Gene Colan (p. 10). Probably the second ever published Gene Colan's work. Possible Klein inks also per Vassallo. Further info on his Blog: