Trama

The team of people who saved Winter's life reassemble in the wake of her surrogate mother's passing in order to find her a companion so she can remain at the Clearwater Marine Aquarium.

It has been several years since young Sawyer Nelson and the dedicated team at the Clearwater Marine Hospital, headed by Dr. Clay Haskett, rescued Winter. With the help of Dr. Cameron McCarthy, who developed a unique prosthetic tail for the injured dolphin, they were able to save her life. Yet their fight is not over. Winter's surrogate mother, the very elderly dolphin Panama, has passed away, leaving Winter without the only poolmate she has ever known. However, the loss of Panama may have even greater repercussions for Winter, who, according to USDA regulations, cannot be housed alone, as dolphins' social behavior requires them to be paired with other dolphins. Time is running out to find a companion for her before the team at Clearwater loses their beloved Winter to another aquarium.—Warner Bros.

Three years after saving Winter, Sawyer (Nathan Gamble), now aged 14, gets a chance for a scholarship to the elite SEA Semester program, which involves three months at sea doing marine mammal research, after impressing his cousin Kyle's (Austin Stowell) advisor Dr. Miguel Arroyo (Carlos Gómez) when champion surfer Bethany Hamilton (in cameo) swims with he and Winter. Sawyer is reluctant to go because he is concerned about leaving Winter. Winter needs attention and shows signs of stress and loneliness, especially after her older companion, Panama, dies. George Hatton (Charles Martin Smith), a USDA inspector, insists that Winter must be matched with a new companion within 30 days or be transferred elsewhere. However, Winter's behavior has become unpredictable, even dangerous: when Sawyer tries to get her out of the tank to prepare to make her a new prosthetic tail, she becomes aggressive and knocks him into the water. Dr. Clay prohibits Sawyer from swimming with Winter. Winter spends weeks in isolation, and despite people not being allowed to visit her, Sawyer allows Susie (Taylor Blackwell), a new volunteer, and her grandfather to see her; Hazel (Cozi Kuehlsdorff) becomes slightly jealous, because she has feelings for him.

A 14-year-old Sawyer (Nathan Gamble) gets a chance at a scholarship to attend an elite SEA Semester program which involves three months at sea to do marine mammal research. Sawyer was once instrumental in saving Winter, is now an integral employee at the Clearwater Marine Aquarium / CMA, and is training new volunteers at the aquarium. CMA is now a larger, more modern, and well-funded aquarium

He lands the scholarship after impressing his cousin Kyle's (Austin Stowell) advisor Dr. Miguel Arroyo (Carlos Gomez) when champion surfer Bethany Hamilton swims with him and Winter. Kyle had recovered from his injury and depression since he was wounded in the army three years earlier, and the marine therapy was a big part of his recovery. Sawyer is reluctant to go because he is concerned about leaving Winter.

Sawyer wants to go but is concerned about leaving Winter, another CMA dolphin he helped save three years earlier, who has lost her tail. Winter has a friend at CMA named Savannah. Like Winter, Savannah cannot return to the ocean. Savannah is deaf and is quite old for a dolphin. She is expected to be at least 40 years old. Savannah has some health issues, and it appears by Winters erratic actions that she is concerned about her dolphin friend Savannah.

Winter needs attention and shows signs of stress and loneliness, especially after the death of her older dolphin friend, Savannah. Winter stops eating much and refuses her prosthetic tail. Her health starts to deteriorate for these reasons.

A George Hatton (Charles Martin Smith), a USDA inspector requires that, for health reasons, Winter must be matched with a new female companion within 30 days or be transferred elsewhere. However, Winter's behavior has become unpredictable, even dangerous: when Sawyer tries to get her out of the tank to prepare to make her a new prosthetic tail, she becomes aggressive and knocks him into the water before Phoebe (Austin Highsmith) jumps into the pool and rescues him. Dr. Clay (Harry Connick, Jr.) at CMA orders Sawyer not to swim with Winter for a while.

Winter spends weeks in isolation, and despite people not being allowed to visit her, Sawyer allows Susie (Taylor Blackwell), a new volunteer, and her grandfather to see her. Hazel, who has feelings for Sawyer, becomes slightly jealous due to Sawyer getting attention from another girl.

Soon after, CMA rescues a severely sunburned and beached dolphin spotted by a girl named Mandy (Julia Jordan). Mandy has a bad sunburn and some respiratory problems from being stranded in the sun too long with her blowhole mostly exposed. They name the Dolphin Mandy, to which Sawyer, Clay and his daughter, Hazel (Cozi Zuehlsdorff) hope to be Winter's companion. Everyone at CMA stakes their hopes on Winter being paired together with Mandy in order to satisfy the USDA and improve Winter's health.

Mandy's rehabilitation at CMA goes well, so Clay contemplates releasing her soon, causing alarm for Hazel in particular. She wants Mandy to stay with Winter for a short period of time to keep her from being transferred, even though she can return to the ocean.

Lorraine advises Hazel that no one spends any more time at a hospital than they need to and encourages her to talk with her father. Hazel assertively yet respectfully asks Clay to let her view Mandy's medical records, which he does. Clay, Sawyer, and Hazel test Mandy's readiness by giving her three live fish, which she catches effortlessly, so they reluctantly decide they must release her. Clay puts Hazel in charge of her release.

Clay discovers a pod of dolphins headed for beach and plan to release Mandy by the next day. Mandy receives a goodbye "ceremony" while she swims out to sea.

Hazel and Sawyer break the rule and swim with Winter, who seems improved and is no longer aggressive. Dr. Clay catches them and scolds them, but then states that it does not matter, because Winter is to be transferred to a marine park in Texas since CMA has no companion for her.

Meanwhile, Sawyer wins the coveted scholarship to attend SEA Semester, so his mother Lorraine Nelson (Ashley Judd) throws him a party. But he still can't decide whether to go because he is too upset. Dr. McCarthy (Morgan Freeman) shows him an old watch which must be tapped to keep ticking. Using this as an example, he encourages Sawyer to "shake it up now and then" and try new things in life.

During the party, Dr. Clay receives word that another female dolphin has been rescued. This one is so young that she has not yet learned how to hunt, so she cannot be returned to the wild. Thus, she represents another hope of companionship for Winter. They name her "Hope."

Also, in a side plot, Sawyer and Hazel rescue a sea turtle from some fishing line and name her Mavis. Rufus (the aquarium pelican), on the other hand, develops a crush on Mavis, even watching her during a CT Scan. As Sawyer and Hazel release Mavis, Rufus, flies out to sea following her.

Dr. Clay gets an extension to keep Winter from being transferred, and CMA tries to introduce Hope as her new companion. But Hope panics and circles the pool at high speed, causing Winter to go into a dangerous panic as well. The staff quickly separates the two dolphins.

To see what went wrong, the CMA staff analyzes the video recording. They realize that Hope did not know what to make of Winter because Hope's echolocation sensed Winter had no tail and moved differently from other dolphins. Sawyer wants to try a new prosthetic tail, but some think it could make Hope panic even more. After debate, everyone finally agrees to try it.

In her second meeting with Hope, Winter wears the new prosthetic tail, designed by Dr. McCarthy. A huge crowd, including George, is present to watch, and eventually the two dolphins accept each other. Everyone rejoices that Winter can stay at CMA now that she has a companion.

With his uncertainty about Winter resolved, Sawyer decides to go to the SEA Semester program, but reassures her that he will be back. Hazel says goodbye to him by releasing helium balloons and holding up a sign, and Sawyer sends her a text message saying, "Thanks, Hazel. You're the best!", causing her to blush as she smiles to herself, while Rufus returns to the aquarium. As Sawyer, Kyle and Lorraine drive away, Hazel quietly affirms she will really miss Sawyer.

Real-life footage shown at the end includes Mandy's actual release, Hope's rescue, a sea turtle named Mavis and her release, Winter wearing the new prosthetic tail, and amputees interacting with Winter.