the Plot to Kill John Wilkes Booth

Many conspiracy buffs put Edwin Stanton in the mix of the plot to kill Lincoln. Nothing could have been further from the truth. The evidence easily proves his innocence but opens his involvement in and even darker plot of his own creation: the quiet extermination of the assassin, John Wilkes Booth. With the actor dead, Stanton's secret would remain forever hidden. But what was it he wanted hidden?