The new Prime Video series Countdown wastes no time setting the stakes. In the very first episode, viewers are introduced to Robert Darden, played by former This Is Us star Milo Ventimiglia, only to see his character killed off in the opening scene in a shocking way.

Ventimiglia was a surprise casting, as he was never formally announced to be a part of the series.

Series creator Derek Haas explained in our interview with the cast why Ventimiglia was cast for a brief but pivotal role in the opening scene.

Why Milo Ventimiglia’s role ends in the first episode

“If you’ve met Milo, what you get in two seconds of meeting him and also two seconds of meeting him on screen is this warmth and this personality and this depth of character that makes audiences like him right from the jump. And if we weren’t going to be around him very long […] I thought that was so important. But the second half of that is that he’s got an actor action star’s mentality. So he goes right from really great character to cool action star in the same scene. So it was the perfect opening.”

Ventimiglia’s character is a Homeland Security officer whose death in broad daylight sets off the series’ central investigation.

Jensen Ackles’ character is hiding a deadly secret

Jensen Ackles stars as LAPD detective Mark Meachum, who’s recruited to a secret law enforcement task force following Darden’s murder. Meachum’s story is further complicated by a personal health crisis.

“I like the twist because it’s not just, I think we’re used to seeing sometimes [with] these characters, they’re just crazy, so that’s why they act so cavalier and that’s why they act like a maverick and have problems with authority and all that stuff is just because wired that way,” he told us. “I like the fact that there’s a reason behind him acting the way that he does and harboring this kind of deadly secret. And it does give him the ability to act out, and to take risks, and to take chances, and put his team in maybe dire situations that he wouldn’t normally do if he wasn’t on his way out, so to speak. I liked that little twist to the character and what it brought to the story. It was definitely something that hooked me from the beginning when Derek was telling me about the story.”

Eric Dane on the mythology behind Meachum

Eric Dane plays Nathan Blythe, the FBI director overseeing the task force. He shared how Meachum’s reputation influences the narrative.

He told Ackles during our interview, “I also think what’s great about your character is you allow for the mythology to develop around you where a lot of the character sort of traits come from the way others are reacting to you and the stories that others tell about you, specifically my character and the task force we had prior to the one that I’ve set up currently.”

What ‘Countdown’ is about

The official description for Countdown reads: “When an officer with the Department of Homeland Security is murdered in broad daylight, LAPD detective Mark Meachum is recruited to a secret task force, alongside undercover agents from all branches of law enforcement, to investigate. But the hunt for the killer soon uncovers a plot far more sinister than anyone could have imagined, kicking off a race against time to save a city of millions.”

Jessica Camacho, Elliot Knight, Violett Beane and Uli Latukefu also star in the series.

The first three episodes of the season are streaming now on Prime Video, with new episodes dropping weekly on Wednesdays.