During the NSF raid on Liberty Island, Harley Filben was brought to the north docks with the help of a drifter woman to serve as an informant for UNATCO on NSF activity on the island. Afterwards, Filben is seen in the subway station at Battery Park and later at the Underworld Tavern in Hell's Kitchen.
When JC is tasked with finding Stanton Dowd, he is told that Filben is an aide to Dowd and might know how to contact him. JC meets Filben at the Underworld Tavern, where Filben reveals that he was working for the NSF all along, as well as for the Illuminati. Filben agrees to contact Dowd and arranges a meeting between JC and Dowd at the ruins of the Osgood and Sons storefront. Filben also reveals to JC that the Midnight Sun reporter Joe Greene is really a UNATCO informant.
Harley Filben can be encountered four times during the course of the game. However, only the fourth encounter is required. As a story-essential character, Filben is invincible throughout the entire game.
- Liberty Island
- Filben is found on the north dock of Liberty Island and will pass information to JC regarding NSF activity on the island if given the password "Iron and Copper." Filben will also provide the key to enter the front doorway to the Statue complex, if JC promises that the NSF commander, Leo Gold, will be left alive.
- Meeting Filben is a secondary objective. Completing the primary objective before meeting him will result in a different set of dialogue when he is then encountered. He will then tell JC, "Why the hell'd I come here if no one needs my help?", to which JC will reply, "I found a back way into the Statue, but I'm sure UNATCO appreciates your dedication."
- Battery Park (second visit)
- JC Denton can encounter Filben a second time in the Battery Park subway station. Here, if JC does not have the password needed to obtain the code to the phone booth, Filben will sell the password to JC for 500 credits.
- Filben will say that UNATCO is likely targeting Juan Lebedev, who owns a terminal at LaGuardia Airport. Filben will also tell JC that the NSF has "some of your buddies at UNATCO" on their payroll, but will not mention who specifically.
- Hell's Kitchen (second visit)
- During the second visit to Hell's Kitchen, Filben can be found in the Underworld Tavern. He will say that UNATCO is about to raid the area.
- Hell's Kitchen (third visit)
- During the third and final visit to Hell's Kitchen, Filben is once again found in the Underworld Tavern. He reveals that he was working with the NSF all along, and confirms that he also works for the Illuminati.
- Speaking to Filben is required for mission progression and will initiate the secondary goal of killing Joe Greene. If JC kills Greene and reports back to Filben, Filben will say, "Man, you really did change sides. Never would've thought it possible."
- If Filben was never previously encountered, the initial dialogue with Filben will be different. He will know who JC is and tell JC, "I'm an agent myself, a double-agent... I report to the NSF and the Illuminati."