He is a young professional musician; while not actually a bad person, Larry has spent much of his life being reckless, immature and self-centered. These qualities are a frequent source of frustration for his friends and family; in fact, they are often noticed and pointed out by people he has just met.
Underneath, Larry is aware of his less-than-honorable tendencies, and disgusted by them, though he does not believe that he is capable of changing for the better.
On the eve of the superflu outbreak, Underwood had written and recorded a breakout hit titled "Baby, Can You Dig Your Man?".
With the success of his first single, Larry has descended into a decadent lifestyle practically overnight. He shuts down a wild, drug-fuelled party raging at his rented Malibu beach-house and flees from his debt to a drug-dealer, all the way to his mother's house in Manhattan, in hopes of laying low for a while. Alice Underwood has not seen her son in years and knows his habits all too well, but grudgingly agrees to shelter him until his next advance check comes in.
Unfortunately, during Larry's stay in New York the plague hits and brutally wipes out the population of the city, including his mother.
In the waning days of the plague Larry meets a middle-aged, pampered socialite named Rita Blakemoor. Lonely and desperate, the two become lovers, and decide to escape Manhattan before all the bodies rotting in high summer make it even more unbearable to stay.
As a travelling companion Rita turns out to be neurotic and high-maintenance. She suffers mood-swings and is hooked upon an alarming variety of pills. Larry is frequently exasperated by Rita's neediness and complete lack of common sense. At the same time, he is earnestly trying to become a better person, and rises to the challenge of taking care of her. By July 4th they have escaped Manhattan and reached Bennington, Vermont, where Rita overdoses and dies in the night. Although her death is "seventy percent accident and thirty percent suicide", Larry still feels responsible, and the incident haunts him for a very long time.
Alone now, Larry travels aimlessly towards the ocean and reaches Maine, where he is stalked by two other plague survivors: Nadine Cross, a mysterious grade-school teacher, and Leo Rockway, a traumatized feral boy she has adopted (she refers to him as "Joe" because he cannot tell her his real name.) Leo carries a butcher-knife and repeatedly expresses the desire to attack Larry with it; eventually, when Nadine loses control of him, he nearly succeeds. After a rough introduction and an uneasy truce, Larry reluctantly agrees to let them both travel with him.
Larry is attracted to Nadine almost immediately, and the feeling is mutual. But Nadine rebuffs his advances, initially finding Larry to be shallow and self-centered. There are other, more sinister reasons Nadine refuses to permit any relationship between them, but she never elaborates on them further.
Meanwhile Larry has a series of breakthroughs with Leo; as the boy gradually begins to trust and bond with Larry, he begins to recover his ability to speak, albeit in monosyllables.
On their way to the Stovington Plague center in search of other survivors, Larry's group passes through Enfield, New Hampshire where they are joined by a young widow named Lucy Swann. They realize they have all been sharing the same nightmares about Randall Flagg, and the same dreams of Mother Abagail.
The Stovington trip turns out to be a fruitless venture, as all within the facility are dead. But Harold Lauder, Fran Goldsmith, Stu Redman and Glen Bateman have left instructions that they are heading for Hemingford Home, Nebraska, and the group decides to follow them there. Along the way, Larry finds himself the reluctant leader of an ever-increasing band of survivors; using Harold's signs and clues, he is able to lead them halfway across the continental United States. Their destination changes one more time to the Boulder Free Zone.
Just before reaching town, Lucy confronts Larry about his fixation upon Nadine. Despite the fact that Lucy and Larry are now lovers, she has no delusions about the nature of their arrangement, and knows that Nadine is both more attractive and alluring than her, while she herself must seem common and cheap by comparison. Larry does not deny any of this, but protests candidly that he "loves her as much as he can." Lucy declares that she would support his relationship with Nadine, free of any grudges or ill-will, if only Nadine would reciprocate his feelings, since love is the only thing that will get any of the survivors through the post-plague ordeal. She does, however, warn Larry not to let himself get hurt in a fruitless pursuit of Nadine.
Later on in Boulder, Larry is one of seven people elected to the Boulder Free Zone Committee. Accepting the nomination took a great deal of persuasion from Stu Redman, but Judge Farris recommended him highly, due to the leadership potential he showed guiding his group of survivors across the country.
Eventually Nadine realizes she underestimated the quality of Larry's character, and missed out on her chance with him. Nonetheless, one night, in a desperate attempt to break Flagg's hold over her, she tries to seduce him. But Larry demonstrates a great leap in his maturity by rejecting her advances, choosing instead to remain loyal to Lucy.
Prompted by psychic impulses, Leo warns Larry that Harold is up to no good in Boulder, and that the details are "all written down", urging him to join forces with Fran Goldsmith. From Leo's clues they guess that Harold has been keeping a diary, which they find after breaking into his house. But they are unable to tease from it the specifics of Harold's plan: that he plans to assassinate the entire Free Zone Committee with a dynamite bomb. Larry survives the bombing incident without a scratch and feels extreme self-loathing about doing so, when so many other Zoners are slain, maimed and injured.
Just before Mother Abigail passes away, she summons Larry along with Glen, Stu, and Ralph Brentner, informing them that they must travel westward to stand against Randall Flagg. Larry is to be Stu's second-in-command, and ends up leading the mission after Stu breaks his leg and must be left behind.
Captured and brought before Flagg, Larry is sentenced to public execution by dismemberment. However, Larry's post-plague experiences have made him a very different person, and he prepares to meet death with peace, dignity and resolve, openly defying Flagg to the last.
The execution is interrupted when the Trashcan Man arrives, hauling a nuclear warhead out of the desert and into the assembled crowd. The "hand of God" detonates the weapon, destroying Las Vegas and vaporizing everyone at ground zero, including Larry.
The following spring, back in Boulder, Lucy Swann gives birth to Larry's twin children.
Larry Underwood is portrayed by Adam Storke in 1994, in The Stand (miniseries)