She is an interesting character who demonstrates a little of 19th Century USA History.

Alma Garret hires her to be a tutor for the orphan Sophia whom Alma has taken under her wing. In the meantime the Garret family back east has subverted Isringhausen to gather evidence against Alma to show that she plotted the death of her husband to gain his lucrative mining claim.

At the camp she and Alma fall out and Alma fires her. Isringhausen stays on to spread stories against Alma so Isringhausen can further her employment from the Garrets on the East Coast.

Then Al Swearengen indentifies Isringhausen as a Pinkerton Agent and even this is too low for Al. The Pinkertons are probably after Al for some misfeasance that he committed years ago.

The Pinkerton Dectective agency was a powerful entity in the 19th Century. It was used often in labor strife and the most outstanding example was the private Pinkerton Army sent to Homestead, Pennsylvania, to break the stike in the Carnegie steel mills.

So powerful was the agency that it had more agents than the U. S. Army.

It was used against the Molly Maguires, also, in the Pennsylvania coal fields and in numberous other strifes. There is a movie, the "Molly Maguires" starring Sean Connery and Richard Harris about this period in history.

Many states banned private armies as a result of the Homestead Strike and Ohio actually banned the Pinkertons.

I suppose in the Deadwood series, the Pinkertons are keeping an eye on labor activities in the gold fields in Dakota. Also a victim of mining fraud brought the Pinkertons into the Deadwood series.

The Pinkertons were also involved in many other hunts for criminals. Pinkerton men are frequently referred to in the 1980 film about Jesse James and his gang, "The Long Riders."

Charlie Siringo was a famous Pinkerton agent, and since he shows up in "Butch Cassidy and the Sundance Kid," although the Pinkertons were not named in that movie, history shows that the super posse was a Pinkerton operation.

In July 2003 Securitas AB acquire both Burns and Pinkerton and formed a new operation, making it one of the largest security companies in the world.