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- “When you take engines built by aliens a hundred thousand years ago and hire a war criminal to bolt them onto the ship, you can't expect predictable behavior!”— Henry Glassman
When a Forerunner artifact was discovered by Fireteam Crimson, Glassman examined it after it sent an EMP throughout the ship. Upon making contact twice with the artifact, he was seemingly dissolved by it in a manner similar to a Forerunner weapon's incineration. However, instead of dying, he was teleported to the surface of Requiem and found at the mercy of Jul 'Mdama. Glassman offered to help Jul in exchange for his life. While discussing plans with a subordinate named Gek 'Lhar, Jul implied that he would eventually kill Glassman when he was done using him to release The Librarian. Glassman was then strapped with an explosive vest and had a restraining collar attached to his neck to keep him in line.
After a small amount of noting how frugal his equipment was, Glassman managed to activate a shield around the Shrine. As the Sangheili kneel down in admiration and Jul reached out to touch the shrine, Glassman took advantage of their distraction to run for it as he tore off his restraining collar. Jul soon realized his disappearance after the shrine shield repulsed him. Glassman managed to make it out of the complex, only to run into two Sangheili waiting at the entrance. Thankfully, his would-be executioners had also captured SPARTAN-IV Gabriel Thorne, who regained consciousness and saved Glassman. Unfortunately, as a host of Sangheili charge towards them, Jul's second-in command Gek 'Lhar, remotely armed the vest. Thorne managed to tear the vest off Glassman and threw it at the pursuing Sangheili as they managed to clear the explosion.
The two then made their way to Galileo base. However, the long journey exhausted Glassman. As they took a short rest, they are ambushed by Gek. Thorne fights hand-to-hand against the Sangheili before knocking him down and attempting to crush his head with a rock. Gek managed to turn the tables and instead slammed the rock on Thorne's chest, knocking the wind out of him. Glassman attempted to reach for Gek's discarded energy sword but the Sangheili stepped on his arm. As Glassman cried out in pain, Gek moved to finish off Thorne, only for Fireteam Majestic to turn up and shoot him in the back, killing him.
Majestic then escorted Glassman to a Pelican so he could return to Infinity. Just then, Captain Lasky appeared via hologram to order Majestic to rescue Doctor Catherine Halsey.
When Glassman returned to Infinity, Jul had set Requiem to collide with the sun and take Infinity with it. Glassman determined that there are two artifacts on Requiem similar to the one on the ship, holding it in place. If the two artifacts are deactivated, it would free Infinity. Fireteams Crimson and Majestic both agreed to undertake the task. After their successful op on Requiem, they raced back to Infinity onboard Pelican dropships. As soon as they were inside the hanger, Infinity quickly made a slipspace jump, barely clearing the supernova caused by Requiem's collision with the nearby star.
Glassman later examined one half of the Janus Key recovered by Majestic and concluding that the artifact was inert and molecularly incomplete.
- In Halo 4, Glassman was voiced by Jeff Doba.