Arguably the most famous dolphin in America, Winter became a cause célèbre as a little pup in 2005 when she was rescued from a crab trap that cost her her tail.

She made her film debut in 2011 in the critical and box-office hit Dolphin Tale, which recounted her rescue and rehab at Florida's Clearwater Marine Aquarium (CMA), where she was fitted with a prosthetic tail.

Today, Winter is a bona fide superstar, the most popular attraction at the CMA, which draws upward of a million visitors a year, and she's seen as an inspiration by thousands of children who have suffered the loss of a limb. (Surfer Bethany Hamilton, whose left arm was bitten off by a shark, makes a cameo appearance in the film, while the extras include scores of other amputees, some fitted with artificial limbs.)

This weekend, Winter is bound to make more headlines with the release of the sequel, Dolphin Tale 2.

Charming, emotionally resonant, yet nowhere as fresh and dramatic as its predecessor, Dolphin Tale 2 reunites director Charles Martin Smith with most of the same - human and animal - cast, including audience favorite Rufus, the most willful, nosy, and pushy pelican you're likely to meet.

The film introduces two lovely newcomers, ingenue dolphin thesps Mandy and Hope.

Also based on Winter's real life, Dolphin Tale 2 opens with the death of her elderly adoptive mother, Panama.

Winter falls into a deep depression in the weeks that follow, a despair that also affects her closest human friends, teenage CMA volunteers Sawyer Nelson (Nathan Gamble) and Hazel Haskett (Cozi Zuehlsdorff), whose father, Dr. Clay Haskett (Harry Connick Jr.), founded the aquarium with the support of his gruff dad, Reed (Kris Kristofferson).

Panama's death provides the film's dramatic tension. Since by law dolphins in captivity must always live with a companion, Clay is told that Winter may be taken away and paired up with a female dolphin at another facility.

Dolphin Tale 2 also develops several cute subplots involving the rescue of a beached and severely sunburned female dolphin (Mandy) and the unlikely (and platonic) love story between Rufus and newly rescued sea turtle Mavis.

Hope - figurative and literal - enters the picture when a very young female bottlenose dolphin pup is rescued. Named Hope, she becomes the top candidate to live with Winter. Will the two dolphins get along?

The Dolphin Tale movies make for a sweet companion to important documentaries such as The Cove and Blackfish that expose the cruelties faced by marine mammals in captivity.

After all, CMA is not an amusement park. Its mission, as Clay repeatedly tells the audience, is to "rescue, rehab, and release" the animals it takes in. All are released, except the few such as Winter and Hope that are ill-equipped to survive in the wild.

Children will revel in Dolphin Tale 2 with its rapturous, lovingly filmed sequences of dolphins playing, swimming, and generally frolicking about with each other and with their human friends.

Yet, despite its stunning underwater photography, its great ensemble cast, and its good heart, Dolphin Tale 2 falters when it comes to drama.

The grown-ups are likely to doze off.

Dolphin Tale 2 **1/2 (out of four stars)

Directed by Charles Martin Smith. With Nathan Gamble, Ashley Judd, Morgan Freeman, Harry Connick Jr., Kris Kristofferson, Carlos Gómez. Distributed by Warner Bros.

Running time: 1 hour, 47 mins.

Parent's guide: PG (mild action sequences, one intense scene of animals in peril).

Playing at: Area theaters.