Jessica Kensky was an oncology nurse and marathon runner. And on that day in Boston in 2013, where she was a spectator at that city’s famed marathon, she was also a newlywed.

One of the bombs that tore through the crowd that afternoon took her left leg. Her right leg was wounded and later amputated. That might have been challenging enough, but it was only the beginning.

Her new husband, Patrick Downes, a doctoral student and marathoner, was by her side. He lost his left leg in the blast.

The aftermath brought so many surgeries they lost count. They lived at Walter Reed National Military Medical Center in Bethesda, Md., for three years. Kensky, now 36, said there were times she felt she could not go on. Life seemed to consist mostly of preparing for surgeries, having surgeries and recovering from surgeries.

But over time, Kensky found that a few things brought her joy. One was her service dog, Rescue. Another was working on the surprising project she and her husband had settled on as a way to tell the world her story: a children’s book.

“Jess was in this incredibly dark place, and I didn’t know anything I could say that would make her feel comforted or happy,” said Downes, 34. “But every time we started working with our [book] agent, she’d always be up for that. It reminded us we still had thoughtful, analytical brains. It felt good and right.”

The result is “Rescue & Jessica: A Life-Changing Friendship,” which is a window into Kensky’s challenges and ongoing recovery, written in terms kids can understand and not be afraid of. It’s a meditation on kindness, acceptance and loyalty. And in the end it’s a story about hope.

The book, aimed at kids ages 5 to 9, shows the relationship between a fictional tween girl named Jessica who lost her legs, and her service dog Rescue. The story unfolds as the two nervously meet and form a bond, and eventually come to rely on and, as the book says, “rescue” each other. The book does not mention the bombing or say how the character’s legs were injured.

This is a second wave of celebrity for Rescue, who won ASPCA’s Dog of the Year award last year.

The ASPCA published a video highlighting “the animal and human heroes the ASPCA is honoring this year.” (ASPCA)

Kensky and Downes have been in the spotlight often since they were wounded. Their journey has been followed by the news media, and their stories are featured in the HBO documentary “Marathon: The Patriots Day Bombing,” and the movie “Patriots Day,” starring Mark Wahlberg.

While they have appreciated the public attention and support, they also wanted to tell their story their own way. They said the idea for the book came from the steady stream of kids who approached them to pet Rescue and ask about their prosthetics.

“Kids come up to us all the time, especially in warmer weather when we’re both wearing shorts,” said Kensky, who a few months ago returned to work part-time as a nurse at Massachusetts General Hospital. “Kids have genuine curiosity, they are trying to make sense of their world. They genuinely want to know if we hurt.”

When Downes was wounded, he was in his last semester earning a doctorate in clinical psychology with a specialty working with children. He says his interactions with them, particularly their honest and thought-provoking questions about his artificial limb, has reminded him that he still has “a gift to share with children.”

“It’s a totally new experience for them,” Downes said. “We would invite them to explore our prosthetics, and it demystifies it for them. The instant they’d touch it, they would smile because it isn’t scary anymore because you’ve allowed them to understand it. While adults might discriminate based on disability, kids welcome it. They think it’s cool.”

Working on the book started to help pull Kensky out of her hopelessness, she says.

Kensky said she always thought she’d have children of her own by now, but the bombing threw a wrench into her plans. Doctors have told them that their injuries would likely not bar them from having children, but Kensky and Downes say they are unsure they could meet the physical and other demands of parenting.

“We got married when I was 31 and I was blown up at 32,” she said. “I don’t think it’s an accident we’re reaching out to this age group with the book. If we were on track with our peers, we might have had a kid about this age.”

Another reason Kensky said it felt right to write a children’s book is because in the aftermath of the attack, she felt in some ways like a child herself.

“After we were hurt, we were separated a long time. I felt like a child again — my parents were at my bedside, my parents were making decisions for me. We were so tired and overwhelmed, in a lot of ways we felt like children again. So it felt natural to tell the book in this way.”

The illustrator, Scott Magoon, was running the marathon during the bombing, and while he was not wounded physically, he suffered emotionally from the trauma of the attack, he has said.

Kensky, Downes and Magoon bonded over the book, as all three were committed to making the illustrations as realistic as possible, from the prosthetics and wheelchairs to the scenes of the city, including Boston Common and Fenway Park. There’s also a page in the book that shows the Boston Public Garden footbridge, where Kensky and Downes got engaged.

Working on the book, they both said, was good for them as a couple.

The two met while they were living in Washington, D.C., and said a lot of their early dating life was spent jogging around the D.C. monuments and the Tidal Basin.

Since they were wounded, there have been plenty of positive moments in their lives. They are grateful to be alive: Three people were killed in the attack. Their friends and families rallied around them in a way they said they can never repay or even express adequate gratitude for. They even went back and completed the Boston Marathon in 2014 using handcycles, arm-powered bicycles. Patrick competed in other years on a handcycle, and in 2016, completed the marathon on a prosthetic running blade.

But along with the good moments, the physical and emotional trauma is always present.

And even though they seemed to go through the same horrors in the bombing, they experienced it differently. Studies show that couples who experience significant life trauma often pull apart rather than together in the wake of a tragedy.

Kensky and Downes didn’t want that to happen to them.

“We know that on the surface we are two people who went through this super intense thing, we were there the same day and hurt the same day,” Kensky said. “But we’re two totally different people. What feels good or therapeutic to Patrick may not feel good to me.”

So they support and love each other, and go to individual and couples therapy. And they talk about their feelings a lot.

“It has permeated every ounce of our lives,” Downes said. “There’s a lot of sadness to unpack and a lot of rich, positive feelings too, and we can experience those at the same time, not only individually, but as a team.”

For now, they are proud of the progress they’ve made on their own and as a couple. And they have a book they are really proud of, too. They hope people respond well to it, both kids and adults.

They have a tour planned for April when the book comes out, and they have already started speaking with groups of kids about the book.

“It’s cool to see where little minds are going,” Kensky said. “Leaving those talks, we always feel so good.”

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