The challenge for the creators of the new “Poppins” was to recapture the charm of the first film but present it in a way that would feel contemporary to 2018 audiences.

Platt, Marshall and producer John DeLuca chose to invent something entirely original for this new “Poppins.” They moved the time frame to the Depression era — as it had been in P.L. Travers’ books — instead of the Edwardian setting of the 1964 film. That connected the time more with the present day. Also, since the new story was set 20 years later, that let them create a new generation of the Banks family, facing new travails.

Michael Banks (Ben Whishaw), a young boy in the first film but now all grown up, is a recent widower, struggling to raise his three children and about to lose their cherished family home. “So there are many reasons for Mary Poppins to come back into this family and bring her special brand of healing,” says Platt.

In the story (credited to Marshall, DeLuca and screenwriter David Magee), Michael has not only lost his wife, but he is also depressed and feeling like a failure; even sister Jane Banks (Emily Mortimer) can’t help. Mary arrives unexpectedly to lend a hand in her own sometimes brisk, sometimes uncanny way, and with the help of lamplighter Jack and his friends, provides exactly the help that the Banks siblings — and the little Banks children — need.

Once that story was in place, says Platt, “we delved into the world of P.L. Travers and found a treasure trove of episodes and characters that were not yet explored.” That provided fodder for the score and animated sequences.

The nine new songs advance the story and illuminate the characters at every turn. And they are an integral part of the storytelling, Magee, Oscar-nominated for “Finding Neverland” and “Life of Pi,” points out: “A song in a musical is that point where it’s no longer enough to speak in simple language. You have to find it through song.”

“It was actually a blessing for me,” says Magee, who’d never written the book of a musical before, “because I could write the dialogue I wanted and reach that moment where I no longer had the language for what the character was trying to go through, and then I would just look at the composer and lyricist and say, ‘I think this is maybe where a song starts’”

For those songs, Marshall enlisted Oscar-nominated, Emmy-winning composer-songwriter Marc Shaiman and his longtime co-lyricist Scott Wittman, who together won a Tony and a Grammy for Broadway’s “Hairspray.” Wittman confesses that the assignment was initially “terrifying,” but that “the great experience was when we were all together trying to figure out which adventures from the books we wanted to musicalize.”

Mary Poppins herself inspired the tone, Shaiman says. “In the books, the character has this almost mystical, spiritual quality. That permeates the lyrics.” And while they initially wrote songs with a 1930s flavor, ultimately they found that reflecting the period was less important than simply writing “in the style of ‘Mary Poppins.’”

Richard Sherman, who wrote the songs for the 1964 film with his brother Robert, affirms just how central the music is, even to a story with mature themes like “Mary Poppins Returns.” “Walt Disney felt that music was a very special thing,” says Sherman. “It’s the magic connection between the performers, the storyline and the audience. You can hear it in your heart and the melodies stay with you.”

The new score, says Marshall, “has the feeling of the Sherman brothers,” just as the film itself contains many familiar signposts, from the curve in Cherry Tree Lane to the staircase in the Banks home and a hand-drawn, 2D animation sequence. “We were working in the realm of ‘Mary Poppins’ while creating a completely new piece.”

But the new songs reflect the new story. They’re soulful, more emotional, and seamlessly integrated into the narrative.

Blunt, who had worked with Marshall on “Into the Woods,” was the director’s No. 1 choice to play the surprising, insightful, empathetic nanny with the carpetbag and parrot umbrella. She said yes, though she was as terrified about reinventing Mary Poppins as Wittman was about writing the new songs.

“Honestly,” says Blunt, “I thought, ‘I better be her by the time I arrive. I better have it down because there’s some big shoes to fill.’ So how do I pay homage to the first film, and yet carve out new space for myself so that this will ultimately be my version of her?”

She turned to the books, where she discovered a somewhat different Mary from Julie Andrews’ character.

“Mary is super-human, and yet she has these moments of great humanity,” says Blunt. “The great joy of Mary Poppins is that she’s so open to interpretation. She’s whatever you really want her to be, or need her to be, at that moment in your life.

“She makes it a voyage of self-discovery for the family,” says Blunt, “so that they ultimately shift, and change, and learn something, from this enigmatic master plan that she has, which is magical and incredibly life-affirming.”

Miranda and Blunt spent months working with Shaiman, Wittman, Marshall and the other writers before traveling to London for rehearsals, music recording and shooting in early 2017. “We did a week-long workshop with a who’s-who of incredible New York theater actors to ‘kick the tires’ on the songs and the screenplay,” Miranda says. “We learned a lot from that process.”

Joining Blunt and Miranda in “Mary Poppins Returns” are two Disney veterans: Dick Van Dyke, who played chimneysweep Bert in the 1964 film; and Angela Lansbury, who was in “Bedknobs and Broomsticks” and more recently voiced Mrs. Potts in “Beauty and the Beast.” Both pop up in small but important roles, binding this new story to Disney’s legacy.

Van Dyke, 92 years young, says “It was like a trip to the past. Every detail was just the same. This is like bookends for me.”
Each musical number is finely tuned to advance story and build feeling. Miranda introduces us to the setting in waltz time with “Underneath the Lovely London Sky.” The sky’s actually kind of gloomy, but it’s dawn, and the darkness is subsiding. Once Mary Poppins arrives, she takes the overly serious young Banks children into a magical world while singing “Can You Imagine That.”

Later, Blunt and Miranda join forces for a fantasy sequence, performing a music-hall number with animated animals (“Royal Doulton Music Hall”) and teaching the children a lesson that will resonate later (“A Cover Is Not the Book”). At the other extreme, Blunt sings the haunting “The Place Where the Lost Things Go” to the children at bedtime; they’re missing their mother and can’t sleep.

Show-stopping moments arrive with Meryl Streep’s “Turning Turtle” and Miranda’s big dance number with the lamplighters, “Trip a Little Light Fantastic.” Lansbury arrives just in time to remind us all that there’s “Nowhere to Go but Up.”

After years of writing and workshops, the creators of “Mary Poppins Returns” rehearsed for weeks with the cast.

None of this was accomplished in a hurry. It took three years; most of 2016 was consumed with hammering out the story, writing the songs and finding the right actors.

“Then came half a year of dissecting, and then preparing for rehearsals at the end of the year,” recalls Shaiman. “We were still trying out different ideas for songs right up until the next to last day of rehearsals.” Music supervisor Mike Higham was then on set throughout shooting, overseeing the pre-recorded songs or helping guide the actors through live recordings.

“One of the hardest things to do is to make a successful musical,” Miranda recently told the New York Times. “I don’t mean financially successful, I mean artistically. Where all the art forms — the choreography, the music, the dancing, the sets, the songs, all build toward these moments. When they’re all working in tandem, I do not think there is a more thrilling art form, full stop.”

That happened with the first film. And while it’s been a long time since then, no less an authority than Richard Sherman gives his blessing to the new effort.

“It’s about time they did a sequel,” says Sherman. “Mary Poppins should come back and spread the happiness again.”