An everyday guy called Sydney Walker was undergoing Theta wave therapy to cure his insomnia. The problem was that the experimental therapy sent him into a very deep slumber and, having suppressed it for 45 years, his rage became a physical, purely electromagnetic and non-living entity.
The Crackler appeared out of nowhere and drained the energy of a lone building in Manhattan, New York, and destroyed much of it, disappearing soon after. The H.E.A.T. crew investigate. Mendel Craven uses N.I.G.E.L. to analyze the air, and Mendel suggests that whatever attacked the building could have originated from inside. Nick Tatopoulos gets a call from Monique Dupre, who says that the monster is in the city's bus yards. Nick takes Mendel and N.I.G.E.L. over there, while the others stay behind.
The Crackler appears in the bus yards and destroys a few buses. Monique soon meets up with Nick and Mendel, and Monique and Nick go to save some people trapped inside a building from the Crackler, while Mendel sends N.I.G.E.L. close to the Crackler to get a reading on it. Monique and Nick untrap the people, but the Crackler destroys the front of the building and does not allow them to escape. Nick leads everyone to another part of the building, but the Crackler destroys the way to the exit. Nick comes up with a solution and everyone escapes. N.I.G.E.L. catches the Crackler's attention, and so the Crackler destroys it. N.I.G.E.L.'s readings indicate that the Crackler is made up of pure electromagnetic energy. The Crackler chases Monique, Nick and Mendel and corners them. However, Zilla Junior arrives just then. Zilla Junior uses his atomic breath on the Crackler, but it absorbs the energy of Zilla's breath and grows bigger. Junior starts attacking him physically, and brings up a cloud of smoke when he hit it into a parking lot. The Crackler disappeared.
Back at the building, Elsie Chapman and Randy Hernandez are investigating Sydney Walker. They discover that he's quiet, never complains, and that he works with electricity, which he got shocked with all the time but never complained about. When H.E.A.T. comes back together, they theorize that Walker secretly hates his job and everyone around him. Mendel dubs the creature "The Crackler", and Elsie tells Nick about a place where they might find out more about Sydney Walker. Nick, Monique and Mendel go looking for the Crackler, while Elsie and Randy go to find out about Walker. Elsie and Randy ask for Walker, but the secretary denies there was anyone called Sydney Walker in that building. Randy sets off a cherry bomb sound, sending everyone outside, as he hacks into the computer and finds out Walker is in lab 13. They go inside and find two scientists, who reveal that they were trying to cure Walker's insomnia. After they put him to sleep a week before, they were never able to wake him up again. They tried various stimulants to wake him up, and it only managed to cause various spikes in Walker's brainwaves at certain times. The brainwave spikes correlate to the Crackler appearing. Walker is theorized to subconsciously control the Crackler with his extremely suppressed anger.
Walker's brainwaves spike once again, and the Crackler appears near a baseball stadium. Monique, Mendel and Nick use a gun that shoots the same electromagnetism that the Crackler is made up of at it, but it partially fails, as it does make the Crackler collapse to the ground, and the Crackler shoots at them. They escape the van, which gets destroyed, and call to check on Elsie and Randy. Elsie unplugs wires connected to Walker using a special suit, but the Crackler was still at the baseball stadium and was attacking everything in sight due to Walker not controlling it anymore. The Crackler rampages and crouches near a body of water, intending to use its electric attacks, but Zilla Junior suddenly jumps out. Junior and the Crackler fight, as Walker wakes up, with the Crackler still fighting Zilla. Nick, Mendel and Monique conduct their electromagnetic guns at a flagpole, which ends up quickly shooting a beam at the Crackler, who was about to use his attack on Zilla Junior. Junior burrows underground, pops out behind the Crackler, and drags it down. The Crackler surfaces and tries to run away from Zilla. Meanwhile, Walker is getting annoyed by Randy, which has a negative effect on the Crackler. Junior catches up with the Crackler and dodges an electromagnetic jab straight to his face. The Crackler picks up a giant metal globe and prepares to throw it at Zilla. Nick encourages Randy to keep annoying Walker, and so he does until Walker snaps, letting his suppressed anger escape his subconscious. The Crackler throws the globe at Zilla, and he fires his atomic breath at the globe, setting it aflame and launching it at the Crackler, making the Crackler explode.