Harry was apparently a school dropout, telling Kevin he never made it to the 6th grade. At some point he would partner up with Marv and became known as the Wet Bandits, "the most infamous criminals alive". They would be in run with the police but they would always hide and outsmart them at some point. Eventually, they would go to Chicago to rob the McCallisters' neighborhood.
While staking out various houses to rob, Harry disguised himself as a police officer and went into the McCallister home. Whenever he tried to get someone's attention, he was generally ignored as the family hustled to get everything packed.
When a pizza boy came to deliver some pizza to the family, Harry opened the door for him and the pizza boy tried to give him the pizza but Harry said it was not for him. The pizza boy then asked if he was just around for the holidays, to which Harry responded, "I guess you could say that."
Harry finally manages to get Peter McCallister's attention and informed him that the police were checking houses around the neighborhood to make sure that everyone was taking the proper precautions against burglaries. Peter told Harry that they had locks on their doors and automatic timers for their lights. Harry started to ask Peter when his family would be leaving, but before he could, Peter was pulled into the kitchen by his oldest son, Buzz, to eat pizza.
Harry soon managed to get Kate McCallister's attention after she paid the pizza boy. Kate told Harry that her brother-in-law, Rob, transferred to Paris the previous summer and that he was giving the entire family a free trip to Paris to spend time together on Christmas and that they planned to leave first thing in the morning, to which Harry replied, "Excellent." Kate then asked him to excuse her so she could take her problematic son, Kevin upstairs, but Harry said not to worry because he spoke with her husband earlier and that her home was in good hands, then left.
Later on, after the McCallisters left for their trip, Harry got in his van in at with Marv in hat and scarf on the street adjacent to the McCallister house and told Marv that he managed to trick the people in the neighborhood into thinking that he was a police officer and that they told him that they were leaving.
They attempted to make their first move on breaking into the McCallister house, but Kevin, having been left behind, observed their shadows walking alongside the house from the inside, and turned on the lights. A confused Marv acknowledged that he thought Harry said the McCallisters had already left, to which Harry responded positively, saying that they were supposed to leave earlier that morning. Not wanting to take any chances, both burglars flee from the house.
The next morning, they decided to rob the Murphy house, the neighbors across the street from the McCallister house, instead. When Peter McCallister attempted to call the Murphy house in an attempt to reach out to his son, both burglars realized that Harry was right about the McCallisters being gone, and planned to rob the house later that night.
As they left the Murphy home, Marv left their "calling card" by plugging up the kitchen sink and turning it on, leaving it running, much to Harry's disapproval, calling it "a sick thing to do." During a brief argument over the topic, Kevin walked past the driveway as they pulled out, almost hitting him before Marv noticed and stopped Harry just in time. Harry rudely told Kevin to watch where he was going. In an attempt to brighten things up, Harry then wished Kevin a Merry Christmas and smiled at him. Discomforted at how Kevin looked at him, Harry pursued him, knowing that Kevin knew something about them. As they drove up past a church, Harry, not wanting to go into the church, gave up the search.
Later that night, the burglars arrived as planned, but Kevin, knowing they would return, animated and dressed up mannequins and played loud Christmas music to make it look as if the house was occupied. The burglars were confused once again and abandoned the plan.
Coming back the next morning, Harry, sent Marv to investigate the house, knowing something was up since the house seemed completely vacant, despite the uproaring event the night before. As he returned to Harry, a shaken Marv (due to Kevin having played a scene from a film featuring an argument between two gangsters that ended with a shootout, made more realistic by Kevin lighting real fireworks towards the end) told Harry of the situation, and Harry saw it as an opportunity to turn in two outlaws to get something in return.
Remaining there the entire night, as Harry awakened the next morning, he observed Kevin walking out his house to saw down a pine tree in the backyard for a Christmas tree. Recognizing Kevin, he realized that he and Marv had been fooled the entire time. Despite Marv's protests of a child being alone at the house, Harry persisted on proceeding with the burglary anyway, commenting that the house was "the only reason they started working on the block in the first place and ever since he had laid eyes on it, he had wanted it."
After going through their plans with Marv, Harry concluded with them returning around 9:00 p.m. Going through the back door, Harry and Marv tried to ease their way in by attempting to fool Kevin by pretending to be Santa Claus "and his elf" with presents for him. However, Kevin then shot Harry in the groin with a BB gun through the doggy door (causing him to squeal like a pig), followed by Marv getting shot in the forehead. Both enraged, the two realized what kind of kid they were dealing with, and Harry sent Marv to the basement door while he went to the front. As he entered the home, Harry fell victim to various booby traps, such as slipping on the icy steps, getting his hand burnt on a heated doorknob, getting his head burned with a blow torch, getting glue and feathers on him, slipping on Micro Machines, getting hit with paint cans, and tripping over a wire.
After Kevin put a tarantula on Marv's face in an attempt to escape, a hysterical Marv threw it on Harry and it crawled onto Harry's upper chest. Harry did not notice the tarantula and was only intimidated by Marv insanely attempting to hit him with a crowbar, but the tarantula escapes, only enraging Harry and he briefly started whacking him with the crowbar.
As they continued to pursue Kevin, Kevin fled to the Murphys' house. However, Harry outsmarted Kevin, ambushing and catching him. Harry then planned to put Kevin through the same torturous injuries that he put them through, but not before biting off all of Kevin's fingers. However, just as he was about to do so, he and Marv were knocked out by Kevin's neighbor, Marley. As the police drove the bandits away, Harry glared at Kevin through his window.
Escape to New York
A year later after spending nine months in prison, Harry and Marv escaped during a riot and soon arrived in New York while stowed away on a fish truck. They planned on getting a hold of false passports and hiding out in "some foreign country."
Marv decided to change their nickname to the "Sticky Bandits" after taping his hand to stick some change to his hand. Unknowingly, Kevin bumped into Harry passing through a large group of pedestrians. Harry initially failed to recognize him, but was visibly curious.
At an ice rink, Harry called Marv forth and acknowledged to him that they had to change their game, as they were not getting anywhere with stealing goods, deciding to steal cash instead. Marv suggested robbing hotels, but Harry knew that tourists were not guaranteed to have much cash. Harry then suggested robbing a toy store, since they made the most money around Christmas time. Making it to Duncan's Toy Chest, they planned on staying there overnight, stealing the money, and then leaving the next morning.
Harry and Marv finally realize that Kevin was also in New York after seeing the McCallister name on the back of the bag Kevin wore after leaving Duncan's Toy Chest. They chased him down the street, but were tripped up when Kevin broke some necklaces, stripping the pearls off.
Marv and Harry later caught Kevin when he fled the Plaza Hotel after being exposed for having his dad's stolen credit card by the staff. After ripping Kevin's plane ticket, Marv revealed their entire robbery plan to Kevin and their plan to kill him, much to Harry's annoyance. Kevin managed to flee their grasps once again when he caused Marv and Harry to be punched by the same woman that Marv had previously been slapped for hitting on earlier and escaped in the back of a horse-drawn carriage. Harry was initially discomforted knowing that Kevin is around, but Marv eased his worries, as Kevin had no home to booby trap them with, and on top of that, was now alone in Central Park, which nobody could survive at night.
On Christmas Eve, while Harry and Marv robbed Duncan's Toy Chest, Kevin knocked on the window, took a photo, and threw a brick through the window, setting off an alarm. Marv and Harry both unknowingly jumped onto a plank and trash can set up as a makeshift see-saw which sent Harry flying through the air and landing on top of a car.
Harry and Marv pursued Kevin to the roof of his uncle Rob McCallister's house as Harry attempted to trick Kevin into throwing down his camera by promising to leave Kevin alone if he agreed. Kevin did not go through and tricked him by throwing down bricks that missed Harry each time and hit Marv four times. Harry vengefully went around the back and warily glanced at an open window and a fire escape ladder, choosing to jump onto the ladder, thinking the window might be a trap. Harry then slipped and hurt his back due to the rungs of the ladder being soaked in a green slime as he mumbled angrily.
After going through more deadly booby traps, such as tools falling on his head, his head getting burned with a blow torch and dipped in paint thinner, falling from a sawed ladder, getting hit in the face with an iron pipe two times, getting crushed with a tool chest, falling from a burning rope, and getting splattered with varnish, Harry and Marv pursued him. Kevin slipped on an icy surface along the way and they caught him and took him to Central Park.
In the park, Harry, finally having had enough of Kevin, attempted to shoot him and get rid of him once and for all. However, he and Marv were distracted when a pigeon lady threw birdseed at them, attracting an entire flock of pigeons to pick them off, allowing Kevin to escape and leave behind the evidence of their crimes. As the police arrived to re-arrest Harry and Marv, Harry continuously kicked Marv for rambling to the police about their schemes.