SPOILER ALERT: Do not read if you have not yet watched “Storybook Love,” the fifth episode of the fourth season of “This Is Us.”

“This Is Us” star Milo Ventimiglia is a veteran producer and director, having launched a production company (Divide Pictures) more than 15 years ago. But his first time stepping behind the camera on the NBC family drama was in the fourth season.

“I had to approach being a director as a guest: I was a guest on Justin’s set; I was a guest on Sterling’s set; I was a guest on Chrissy’s set,” Ventimiglia tells Variety.

Conversations for Ventimiglia, who has directed a handful of independent projects in the past, to step behind the camera for an episode of “This Is Us” started in the second season. Executive producer and director Ken Olin asked him, “You’re goingn to direct one of these, right?” the actor recalls. And Ventimiglia responded, “I’ll direct if you guys want me to.” But the plan was to get the first few seasons under their belts before they began opening the door to actors to step behind the lens. This allowed the show to set its tone and visual language and give the performers and the audience time to get comfortable with it.

Helming the fifth episode of the fourth season, Ventimiglia had a clear directive: “My job is not to make it look like anything brand new,” he admits. “For me it was about, how do I serve the show? How do I serve the actors and the crew and everybody that I’m so familiar with, but also make it feel like it’s a unique experience for them, having me on set as a director as opposed to just an actor?”

Ventimiglia’s strategy was to “make it fun, make it beautiful [and] get people home early,” he says. But also, he was adament about “overpreparing” in the prep stage — including making a detailed shot list and storyboarding moments that called for it. “That was a little more for me just to have those things so people felt confident in what I was doing. It’s important to let the crew and the producers and everybody know that you’re ready for every scenario and you’re prepared; you’re ready to go,” he says. “I’ve done the homework; I’m not just showing up and winging it on set.”

Ventimiglia adds that being able to be flexible “on the day” of shooting is important for any director, and that was especially important for “Storybook Love,” an episode that saw him moving between big location scenes and smaller, personal family moments, all in the span of a few hours.

“When we’re on the hockey set and we have 300 background actors and we have to keep everybody on the same page and shoot that efficiently because we’re shooting it in the morning and then going back to Paramount to shoot an intimate scene with Susan Kelechi Watson and Ron Cephas Jones in the afternoon, I think those might have been the moments where the bigger set pieces were the more challenging ones,” he says.

Nothing about the episode, no matter how well he knows the show and the characters at this point, let him off easy. He also had scenes that dealt with animals and babies — from Kate (Chrissy Metz) waiting with her son and dog for the special delivery at her house, to the surprise bird visitor in Jack and Rebecca’s (Mandy Moore) house.

“We made a decision to have a practical bird and give the parameters to the trainer. We got so much footage with the real bird, we used the majority of it. But there were a few pieces that were ultimately safer for the bird to just do it in CG. Like when I was moving around and freaking out, you don’t want a real bird there because you can’t communicate with a real bird,” Ventimiglia says.

He also had to carefully create new moments in pivotal characters’ relationships — such as Kevin (Logan Shroyer) and Sophie (Amanda Leighton) as newlyweds, Randall (Niles Fitch) navigating the nerves of bringing Beth (Rachel Hilson) home to meet his family for the first time, and teenage Kate (Hannah Zeile) embarking on a relationship that would alter the course of her life.

“It was important to know exactly what happened,” Ventimiglia says of directing “Storybook Love’s” final scene in which an adult Kate and Rebecca come across a Polaroid from the family dinner featuring Kate’s record store boss-slash-boyfriend. “We don’t necessarily need to know the fine print, but we do need to have an understanding of what happened and what was the impact. Because it was one of the moments in young Kate’s life that put her on one path or another; it definitely impacted her future.”

Ventimiglia also gave the audience its first glimpses at Rebecca and Miguel’s bond that eventually turned into romance, something which has been teased since year one on the show. “It was kind of a big thing when Rebecca and Miguel are in the kitchen and Rebecca’s having a very serious questioning moment of if the family is beyond repair from Jack’s death and Miguel has this really beautiful moment where he’s discovering, too, that you’ve got to get through that bad stuff and you will make it through the other end. But I know we haven’t ever explored that relationship with Miguel and Rebecca; these are the little moments we’re starting to pick up — the friendship and the bond and the camaraderie of them having both been through a hard time,” he says.

Directing “This Is Us” came almost a decade after Ventimiglia’s last directing gig (one that also saw him directing himself), but the process of stepping back behind the camera reaffirmed how much he loves being on set, he says.

“When you embrace a crew and their talents and you trust what they’re going to bring, they’re going to look out for you. Once they know that you’re there to serve them, they’re going to work even harder with you to give you what you need creatively. And it also reminded me, too, of when I do just have this singular job of being an actor, how do I support everyone around me on set, from top to bottom?”

“This Is Us” airs Tuesdays at 9 p.m. on NBC.