"Day of the Cold Sun" is the third regular issue of PKNA. It was written by Alessandro Sisti, and penciled by Claudio Sciarrone.
Lyla Lay and Camera 9 are covering the inauguration of a new energy central in Duckburg. Lyla tries to ask some questions to the secretary of energy Bob Dugan, when an stranger approaches and attacks Dugan's bodyguards. Armored men arrive claiming to be federal agents and face the stranger, who disappears and then they disappear too. Camera 9 gets it all as an exclusive report on tape, which worries Lyla, who then asks the memory disc of the record to keep it safe.
At Channel 00, Camera 9 is congratulated for his work and the footage is taken to the studio to watch it. In other part of Ducklair Tower, Scrooge McDuck tells Donald that the tower is practically filled up, and almost all the tenants have their own staff, so he won't be needed as the caretaker. After Scrooge leaves, Uno calls Donald to the 151st floor to watch the Channel 00 screens, as the tape seems related to some terrorists who have caused damage with urban warfare. When the disc is played at the studio, anything after the "federals" arrival is blank. Lyla tells the weapons radiation may have interfered with the recording, while Angus Fangus blames Camera 9. A disappointed Camera 9 knows the recording was perfect when he handed it to Lyla. Donald and Uno deduce the terrorists must be after the energy center.
Lyla talks to a Time Police officer and ensures him that she deleted the recording, but they must hide as the meddling Angus is passing. Angus is at the cellphone to get an interview about the energy center, but he's being followed by the stranger, who sabotages his car after he gets the interview.
"Angus" arrives to the interview, where he's greeted by press officer Clark Queen and managing director, professor Seamus Hogg, and tells them he knows all about their secret "Cold Sun" project, concerning a system of super cold fusion taken to its highest potential to provide Duckburg with a practically inexhaustible energy source. They accept to show and tell him whatever he wants to not get their secrets exposed in a special edition. However, the real Angus Fangus shows up and the imposter has to teleport away.
After watching Angus' report of the events at Channel 00, Uno analyzes the impostor's disappearance sequence and it leaves tachyonic residue, which makes Donald realize it's The Raider, so he changes into the Duck Avenger and goes to see Lyla as she would know if the Raider has come to the present day. Lyla only gives him vague info and then contacts her superiors, but the Duck Avenger follows her and the Time Police agents see themselves forced to tell him that the Raider escaped and stole a powerful prototype known as an Othership.
The Duck Avenger then responds to a police call asking for reinforcements. The attacker turns out to be the Raider, who wants to talk with the Duck Avenger. The police thinks they are in cahoots, so both caped characters must escape together, and the Raider transports himself and the Duck Avenger to 1238. There, the Raider explains the Othership, a device he carries on his chest, would allow him to travel to alternate universes, but it needs a lot of energy to work, like the one in the energy center. He went there disguised as Angus to explain the scientists how to activate the cold fusion while avoiding an explosion that, in his time, is registered as the destruction of a large part of Duckburg. The Raider explains that the Time Police don't want to stop the explosion to not change history, so he makes a deal with the Duck Avenger to stop the explosion, use the energy to charge the Othership, and as a thank for his cooperation, never return to bother him in present day Duckburg. The Duck Avenger first wants to be sure the Othership isn't something worse and scans it.
After returning to the present, the Raider travels to the next day to arrive when the Duck Avenger has made his mind, while the Avenger himself goes with Uno to have him analyze the scan. Uno cannot analyze so well the 23th century tech and the Avenger is split between stopping the explosion and impede the Raider to steal in infinite realities. Uno finds a peculiarity in the Othership and suggests to use it to hatch a plan.
A few days later, Lyla attends the project as a press guest, and also arrives a man named "Professor Praedatorius", an observer of the World Science Comitee. Before Hogg can activate the Cold Sun, he is frozen with a chrono-paralyzer, and then the Praedatorius unmasks as the Raider while the Duck Avenger comes out of his luggage (it's implied that Uno altered the computer registers to allow Praedatorius' entrance). Lyla knew it was them all along, but let them go so far to know what the Duck Avenger wanted to do, or maybe because she trusts him. The Raider stops the explosion, and the Time Police arrive to find why it hasn't happened. It also turns that Lyla didn't know about the explosion and the Time Police intended for her to also be destroyed as she's too autonomous, and would have been replaced by another unit. The Raider reactivates the Cold Sun, this time stabilized, and charges the Othership, but since it lacks a control system to choose dimensions (the peculiarity found by Uno) the Raider is frozen in the middle of all possible realities. Since the explosion was already averted, it has been deleted from history and trying to restore it would further damage the timeline. However, it's still too soon in history for such an energy to be invented, so the plant is fixed to not work, and nobody will know the cause of the failure.
Lyla gets mail, and it turns out to be photos of her reunion with her Time Police superiors, but the negatives are also there so it isn't blackmail. While she's destroying the pictures, Angus and Donald try to invite her out, but before they fight, Lyla tells them she already accepted to drink some hot cocoa with Camera 9.