Sergeant Roth was a member of the United States Colonial Marine Corps. He was part of a 31 marine platoon under the command of Captain Paget, aboard the combat ship Hasdrubal that landed on the planet Tartarus, kick-starting a massive series of events that led to an all out battle for survival against the Yautja species, Xenomorph organisms and the godlike Engineers.
Before the drop
In the flight deck of the Hasdrubal, Captain Paget informs Roth of the mission; to investigate the planet Tartarus, a Weyland-Yutani-purchased planet under suspicion of illegal prospecting by the rival corporation Seegson.
During briefing, Paget informs the crew of Wey-Yu representative Lorimer's presence and tells them to make a good impression, specifically refraining from any foul-language and trigger-fingers, telling the crew that "this isn't lightholme". Roth later explains to Lorimer that lightholme was the squad's previous operation, in which two allies were lost. Since then, the squad has been "a little gun happy". He also tells him that they should have recuped and resupplied but instead were dispatched to this mission instead. Lorimer asks if Paget is worried about them being too tired to fight, with Roth correcting him that the squad are too eager.
Exploring the planet
Two marine dropships detach from the Hasdrubal and land on Tartarus, with several squads splitting up. Roth, Jhalil and Freebody encounter a large ruin of a tractor unit. The group suddenly encounter lone survivor Laurence Goode, who warns the marines that they never should have come to the planet.
Roth contacts Paget, who had recently encountered a lone Engineer derelict regarding the recovery of Goode. The marines regroup at the excavation site, with Goode explaining that he was part of the excavation team ready to asset-strip until "they" killed every single other member of the team. Roth tells Goode that his actions result in a 6 year penalty, though Goode happily embraces the sentence as long as he get's to leave the planet. Paget orders Sergeant Roth's squad to perform an active search pattern for any other asset-strippers. Roth splits the squad up and sends Delaria to sweep the right, and Stefopoulos, Lee, Rucker and Bonito, to the left.
Paget later contacts Roth and informs him of three missing marines, Chimo, Garland and Herrman. During his search, Roth and his squad find Rucker completely surrounded by Yautja. They open fire and send the hunters into retreat. Rucker explains that the Predators ambushed his group and slaughtered them, though Roth is suspects that Rucker shot Lee.
Plan to secure the derelict
Back at the site, Roth confronts Rucker, telling him that he knows he shot Lee. Rucker remorsefully admits that she accidentally got in his line of fire after trying to shoot down a cloaked Predator. Roth asks if he will report this to Paget, with Roth saying no. Paget decides to send Sergeant Roth and his team consisting of Jhalil, Freebody, Rucker, Singer, Wearing and others into one of their dropships to fly over to the Engineer ship and secure the interior whilst Paget's team approaches the vessel by foot, attempting to sweep the forest using M314 Motion Trackers to flush out the hunters. However, the Elder Cracked Tusk Predator ambushes the dropship and manages to crash it. As the dropship crashes near the quarters of the Engineer vessel, the marines manage to wound the Cracked Tusk Predator and it flees. Roth's squad enters the interior of the vessel and eventually come across the cockpit, containing a sarcophagus-like object. Singer suggests that he would be able to get the ship operational and have the ship leave Tartarus and abandon the Predators.
The Cracked Tusk Predator, unbeknownst to the other marines, was observing them withing the derelict and called for the Predators who were battling Paget's crew to retreat back to the vessel to stop them from lifting it. The Cracked Tusk Predator ambushes the squad a second time but is finally managed to be killed by Humble by shooting it with a Pulse rifle after it's Wristblades get stuck by accidentally lunging it into the sarcophagus. Singer manages to get the ship operational and plans to send it to the nearest USCM facility, Ganymede station.
Sergeant Roth scorns Humble for using a firearm, Humble reassures him that he "killed the big monster".
Awakening the Engineer
Singer is busy attempting to establish comms with the Hasdrubal whilst the other marines wait and discuss matters. One marine, Indelicato, inspects the sarcophagus object against Roth's wishes. The sarcophagus suddenly opens and an Engineer emerges from it. Roth points his pulse rifle at it but Singer stops him. As Indelicato cautiously approaches the massive being, the Engineer suddenly crushes his head, sending the marines into a retreat after their weaponry has no effect on it. They are forced to hide as the Engineer begins taking control of the ship and directing it to a different destination.
Landing on LV-223
Six days later, the vessel lands on the moon LV-223. The Engineer walks out of the vehicle and the marines quickly follow once it is out of sight. Roth immediately orders his squad to set out for shelter, food and water. The group later encounter a small lake of black liquid in a forest, with Singer concluding that their entire surroundings is made up of the black goo. Roth hopes that if they find a water source, the liquid can be extracted from the substance, otherwise the group have little chance of survival.
The marines are suddenly ambushed by a horde of Xenomorphs, resulting in Rucker being taken and Jhalil being gravely wounded. As the group are close to being overrun, they are saved by Geryon survivors Angela Foster and Galgo Helder. The Predator Ahab later reveals himself to the group too, much to Roth and his squad's shock and bemusement at seeing a non-hostile Yautja.
Roth and the team regroup at Foster's base, where they also meet fellow Geryon survivors Chris and Jill. Roth discusses the purpose of the black liquid with Foster as the rest eat. After Galgo reports that the Engineer had visited a temple to reawaken a second Engineer from stasis to kill them, the team formulate a plan to leave the moon.
Angela plans for Ahab and Galgo to distract the second Engineer whilst Angela, Roth, Singer and Humble go to the derelict to deal with the first Engineer. The rest of the team, Wearing, Freebody, Chris, Jill, and Melville are to carry the supplies as well as the wounded Jhalil.
Roth and his team approach the derelict from a distance, the Engineer lingering nearby. Roth realizes that he is not going to be moving any time soon and although Foster suggests waiting him out, Roth volunteers to distract it. He gets closer and fires a grenade at an Engineer temple. The Engineer takes the bait and approaches the temple, giving the rest the opportunity to sneak into the vessel, but not before noticing Roth and firing at him. The Engineer enters the ship, unaware that the rest sneaked aboard and takes leave, stranding Roth.
Roth, dissapointed with the outcome of the plan, is seen slumping against the terrain of the moon, constantly trying to contact the others. He eventually receives contact from Freebody who informs Roth that they were ambushed by Xenomorphs, resulting in Wearing's death and Chris being taken to a hive. Roth later manages to regroup with Freebody and the group. Roth discusses the chances of survivability with Freebody, with Roth remarking that it won't be much of a "last stand". Suddenly, an M577 Armored Personnel Carrier arrives at their junction. Although Roth is initially cautious, the vehicle's drivers emerge to be Captain Paget and Ancane and Roth embraces Paget as she opts to return to the Hasdrubal.
Back at the Hasdrubal, Roth confirms to the marines that Chris has been left behind on LV-223 and wants to return to the moon. Ancane is reluctant, citing the amount of losses received. Roth believes that no man should be left behind and that they owe Chris. The marines launch a rescue mission for Chris and they take a dropship back to the moon.
Roth manages to contact Chris via headset and informs her of her rescue. Chris tells Roth that she has been impregnated and that they should abort the mission, before being suddenly ambushed by a horde of Xenomorphs and later the Second Engineer. In the ensuing chaos, Roth and others manage to rescue Chris whilst the Engineer and a Xenomorph Queen battle. They return to their dropship, only to see it in ruins (previously destroyed by the Engineer). Paget attempts to contact the Hasdrubal with no reply.
Stand-off at the temple
As Paget concludes that the group had lost contact with the ship, the group decide to retreat back to the Engineer temple to set up camp and wait for an automatic freight bus to pick them up.
The Tartarus Predator clan soon arrives onto the moon, seeking revenge from their previous encounter with the marines. After a confrontation between Ahab and the clan leader, the clan side themselves with the marines against an upcoming stampede of Xenomorphs approaching the temple in an attempt to capture Chris. The marines and Predators both put up a tremendous effort against the Xenomorph army but their numbers begin dwindling and the aliens begin seeping through. In a last ditch effort, Chris sacrifices herself by blowing herself up, along with the Queen inside of her, sending the Xenomorphs into a retreat.
The Tartarus clan take their leave alongside Ahab whilst the marines wait at noon for the freight bus to arrive. Roth notices a noise in the horizon, but Paget discloses the sound.