In his day job, Glen is just another cog in the machinery at the Department of Motor Vehicles office in Washington D.C. However, he also has a separate line of work as a "tracker" for Raymond Reddington, presumably using his position at the DMV to access personal information needed to locate people and objects.
In "The Front", Reddington has employed Glen to find Zoe D'Antonio. After spending 45 minutes waiting in line for a meeting with him, Red is upset that Glen has not found her yet. Glen complains that he wasn't given a lot to work with and that he has been distracted because his mother is dying of cancer. Red does not buy it, saying that Glen has made similar excuses, such as his brother-in-law having Legionnaires' disease and his house being flooded, and leaves.
Later in the episode, Glen calls Red and tells him he has found Zoe. When Red meets Glen to receive the information he arranges for a new vending machine to be installed in the DMV waiting area.
Reddington enlists Glen to locate the safe in St. Petersburg which Alan Fitch told him about just before his death. After tracking down the building, Glen asks to come with him for the search, inventing a story that he has never been outside the country since his childhood vacations were always within driving range. Reddington believes him and accepts, and then finds out that Glen was actually raised in London.
After the flight to St. Petersburg, during which Glen insulted the flight attendant, Reddington, Dembe and he search an apartment for the safe. When Reddington states his doubts about the location, Glen explains that he went through Fitch's financial records and found that apartment 221 belonged to him. Reddington points out that he has taken them to apartment 212. When they search the right apartment, Reddington finds a wall safe that contains a business card.
Sensing something amiss about Dembe's disappearance, Red calls Glen to investigate what happened to him. At first, Glen, who is playing Tetris on his computer, doesn't answer the phone. When he does, he pretends to have been interrogated by the FBI and to have given up Reddington just to mess with him before admitting that he was joking. Accepting the assignment, he traces Dembe's last known location to a restaurant and is able to distract a host working there long enough to steal the video recorder. At his office, Glen investigates the recorder and is alarmed. He calls Red to inform him that they have a problem.
Glen ran a credit check on Francesca Campbell and discovered she wasn't married, proving she lied to Reddington about herself.