The novel opens on the night the DC Stars, a fictional NHL team, win the Stanley Cup championship. Lexi Armstrong, the team's 32-year-old head athletic trainer and the first woman to hold the title in the league, celebrates at a downtown club with her close friends, including Piper Mitchell, the Stars' rinkside reporter, and Emerson "Emmy" Hartwell, the first woman to play in the NHL. Riley Mitchell, a 26-year-old defenseman who has quietly nursed a crush on Lexi for years, shares a flirtatious exchange with her, then leaves in an Uber driven by Lamar, a young father supporting his pregnant wife. A drunk driver T-bones the vehicle, and Riley blacks out.
Lexi receives a panicked call from Piper and races to the hospital, where the entire team has gathered. A doctor announces that Riley survived but requires a transfemoral amputation, the removal of his right leg above the knee, because the damage is beyond repair. Asked if Riley will skate again, the doctor offers only a sad smile. Lexi privately vows to get Riley back on the ice.
The narrative jumps forward through text messages and brief scenes spanning July to September. Riley withdraws completely, leaving the team group chat, ignoring his teammates, and skipping mandated meetings. In therapy with Dr. Ledlow, a therapist assigned by the team, Riley cycles through rage and grief, unable to envision himself without hockey. He admits to past suicidal thoughts but says he is no longer having them. Coach Brody Saunders, the Stars' head coach, escalates from gentle reminders to blunt demands until Riley finally attends a meeting at the arena.
At the meeting, ownership announces they will honor Riley's full contract provided he attend therapy, undergo rehabilitation, show up at practices and games, and offer strategic input. Lexi presents a rehabilitation plan citing a real case of another hockey player who skated after an amputation. When Stuart Klein, Lexi's new boss, dismisses and misnames her, Riley insists Lexi lead his recovery. Management agrees. Afterward, Coach privately tells Lexi that Riley's mother reported he had expressed wanting to not be alive anymore, urging Lexi to handle his case with care.
Lexi and Riley begin sessions five days a week at the arena, focusing on strength and balance exercises. Riley arrives on a walker with a temporary prosthetic, self-conscious about his body. Their familiar banter gradually returns. Riley's agent, Marcus, later arranges a reunion with Lamar that provides closure about the accident.
Despite early progress, Riley begins skipping sessions, spiraling after an ESPN segment dissects his injury and his upcoming permanent prosthetic fitting makes his new reality feel irreversible. Lexi drives to his apartment to confront him, and they agree to communicate honestly: He will tell her when he needs a day off, and she will respect his limits.
Riley receives his permanent prosthetic and rejoins his teammates at a Pilates class Lexi teaches, marking his return to group activities. At a dinner afterward, he gives Lexi a lime because she once mentioned liking them, a detail from the night of the accident. At a diner after a preseason game, they share personal histories and create "Riley's Life List" on a napkin: things he wants to experience, including riding a roller coaster, getting a tattoo, and skating again.
Coach secures league approval for Riley to stand behind the bench in a coaching capacity. Riley resists at first but proves valuable, fixing a technique for teammate Grant Everett and offering tactical observations. During an away trip to Miami, Riley grows jealous when a stranger flirts with Lexi at the hotel bar. She follows him to his room, and they sleep together for the first time, agreeing it is a one-night arrangement. Riley confides he has not been intimate since the accident; Lexi reassures him, and they figure it out together.
Brief awkwardness follows, but they resume their friendship. Lexi proposes a friends-with-benefits arrangement: exclusive, no emotions. Riley agrees, though the arrangement quickly exceeds its boundaries. Riley cares for Lexi through a bout of norovirus, and she asks him to stay the night, a first for them. For Christmas, Lexi gives Riley a framed copy of his Life List and custom skates designed for his prosthetic, inscribed with "For all the good days." Riley breaks down and tells Lexi directly about his suicidal thoughts in the hospital.
Riley's first attempt to skate, surrounded by teammates who link arms around him, ends in repeated falls and frustration. Lexi sits with him in the penalty box and asks him to recall learning to skate as a child. He remembers falling and his father picking him back up. Riley says he may not want to try again but adds "another day," and Lexi promises to be there when he is ready.
Lexi rents out Coney Island for an afternoon so Riley can cross items off his Life List. They ride the Cyclone, race go-karts, and share ice cream on the boardwalk. Soon after, Riley tells Lexi his feelings are no longer strictly physical and asks to date for real. She agrees. On their first official date, a bet over pool leads to matching tattoos. Over ice cream, Lexi asks Riley to be her boyfriend, her first ever.
Lexi reveals that her father abandoned her family when she was a child and that she later unknowingly had a prolonged affair with a married man whose wife accused her of being a homewrecker. The experience conditioned her to leave men before they could leave her. Riley responds by revealing the meaning of his constellation tattoo: It maps the night sky on the day he first walked into the arena and met Lexi.
Riley's second attempt at skating succeeds after Lexi obtains a custom lightweight prosthetic with an attachable skate blade, designed by a company that outfits Paralympic speed skaters. He completes multiple laps and FaceTimes his father mid-session. When Coach must leave for a family emergency during an away game, Riley's teammates vote unanimously for him to serve as acting head coach. He guides the Stars to a victory, drawing attention from the Minnesota Vipers organization.
Coach informs Riley that the Vipers want to interview him for a scouting position. Riley tells Lexi, and she reflexively pushes him away, telling him to take the job. Riley recognizes she is reverting to her pattern of preemptively ending relationships. He tells her he loves her for the first time and promises to wait however long she needs. Lexi whispers that she needs air and leaves.
She avoids him for over a week before gathering her friends and admitting she loves Riley. Emmy asks, "What if it's the best thing that could ever happen to you?" Lexi races to Riley's apartment, where he waits in the doorway holding tulips. He tells her he turned down the Minnesota interview because he wants to stay in DC and keep trying to play. They exchange "I love you" for the first time mutually.
In the months that follow, the Stars advance deep into the playoffs, and Emmy and her partner, Maverick, a Stars teammate, announce they are expecting a baby girl. Eight months later, Riley makes his professional hockey debut with the Virginia Comets, the Stars' AHL (American Hockey League) affiliate team. Wearing the prosthetic blade Lexi helped design, he plays six minutes and records an assist in a 3-2 victory. His Stars teammates, having secretly flown home from a road trip, are in attendance alongside Riley's parents and Lamar with his son. Named the game's top player, Riley pulls a folded napkin from his skate, his Life List, and shows Lexi the final three entries: "Get Lexi to like me. Get Lexi to fall in love with me. Get Lexi to spend the rest of her life with me." He clarifies it is not a proposal but a promise. Lexi says yes to all three.