The assassin

"As Van Dorn private detective Isaac Bell strives to land a government contract to investigate John D. Rockefeller's Standard Oil monopoly, the case takes a deadly turn. A sniper begins murdering opponents of Standard Oil, and soon the assassin - shooting with extraordinary accuracy at seemingly impossible long range - kills Bell's best witness, a brave and likable man. Then the shooter detonates a terrible explosion that sets the victim's independent refinery ablaze. Bell summons his best detectives to scour the site of the crime for evidence. Who is the assassin and for whom did he kill?"--