Soldier of Fortune II Double Helix is a first-person shooter video game developed by Raven Software and published by Activision, a sequel to Soldier of Fortune. Double Helix plunges the players into the secret and deadly world of the modern day mercenary as they race around the globe to stop a bio-terrorist organization. The real-life mercenary John Mullins returns to put an end to the new threat of bio-terrorism, with the aid of his new assistant Madeline Taylor.