Few years ago, young Littlefoot along with his adoctive brother Shorty hears a story for his father Bron and his grandparents about longneck alphas and beta who leads new herds of different types of longnecks and takes them on a journey to a valley where all young longnecks go.
In the Great Valley of the present, Littlefoot (Elijah Wood) had a dream which involve a herd of longnecks heading to A place where all different kinds of longecks go to a place with a rock that shapes like a longneck called the Land of Longnecks.
In the morning, Littlefoot and Ducky (Tara Strong) were playing tag and Ducky tried to get him but failed and then she tried to get Petrie (Tom Kenny) but Petrie flew too fast and she tried to get Spike (Mitchell Whitfield) and Tippy (Rickey D'Shon Collins) when they were eating treestars but Spike and Tippy ducked and Ducky falls on the ground and when she saw Chomper (James Arnold Taylor) and Ruby (Grey Delisle) she tries to tag them but when Chomper smells her behind them he warns Ruby that Ducky is gonna tag them from behind and then moved. Ducky spots Cera (Hayden Panetiere) eating and tries to tag her, but Cera knows she was gonna tag her. When Ducky see Littlefoot she chase him in order to tag him. When Littlefoot stopped he saw two longnecks coming into the Great Valley and Ducky triedly tag him. Littlefoot told his friends that he see longnecks coming into the valley and went down to see them.
As the gang heads finally arrived, the meet the longnecks named Longela (Giancarlo Esposito) and Lonsha (Lupita Nyong' O who came to their home looking for Littlefoot, and wants him to journey to the Land of the Longnecks that he had a dream about, and be reuninited with the new alpha and beta longnecks, and they told him and his friends about rogue fast biters (Monolophosaurus) led by their leader named Sharp Claw that Chomper knows are causing trouble by hunting and killing, and Littlefoot must be ready to go today.
During the sky water, the gang starts having a meeting about the rogues that could attack someday and Chomper wants to get even with Sharp Claw, like he did when he got older, and Littlefoot made a decision that he has to go the Land of the Longnecks meets the alpha and beta longnecks that he hasn't met before and says goodbye to his friends and wishes Chomper good luck to take care of Sharp Claw.
As Littlefoot began his journey, he enters through the canyon where he meets a fin back longneck (Amargasaurus) named Amargus (Dee Jay Daniels) who was travel to the Land of the Longnecks cause he had a sleep story like he did.
When Littlefoot and Amargus enters swamp, they encountered a slither (Titanboa) but was saved by another teenage longneck (Alamosaurus) named Alama (Kelly Vitz) and she joins them on a journey.
Back in the Great Valley during the night time, Chomper begins to track down Sharp Claw, and the gang joins him on a search.
Meanwhile a one of rogue fast biters inform Sharp Claw (Andy Serkis) that Littlefoot has began his journey and begins to track him down.
The next day, Littlefoot, Amargus, and Alama journeys towards the jungle where the meet a different other longneck (Argentinosaurus) (Drake) named Argent who was eating plants and joins them to head for the land that they're heading.
Later, Chomper and the other finds themselves heading toward a waste land and knew that Sharp Claw and his pack were around until they encountered another slither (Sanajeh) and was able to get it off their backs as they left the waste land a stopped to rest.
Meanwhile, Littlefoot and the other longnecks he made friends with see other young longnecks journey to the land as they are and catches up to them and keeps heading toward their location.
Later, in the morning, Chomper, and the others awaken until they were sleeping next to a sharptooth (Megalosaurus) and starts running it and was able to hide in behind big rocks and the sharptooth lost track of them, and as the gang waited for the sharptooth to be gone, they meet a different longneck (Bonitasaurus) named Bonris (Michael Angarano) who was on his way to the land of the longnecks.
Meanwhile, Sharp Claw discovered that Littlefoot is travelling with other longnecks and begins to track them down and kill them all.
Later, as Littlefoot and the other longnecks are miles away to the land, they see other longnecks resting and they stopped to rest as well, and Alama meets a handsome longneck (Giraffatitan) named Gititan (Ian James Corlett) and Littlefoot seeing other young longnecks bumps into female longneck (Brontosaurus) named Linga (Danielle Panabaker), and meet her brother, Longin (Bill Switzer) who are the alpha and beta longnecks of their herd, and Longela and Lonsha arrived and told Littlefoot that Longin and Linga are the alpha and beta longnecks they told him about who happens to be his adopted brother and sister and he didn't knew he had more siblings.
Meanwhile, Chomper and the others along with Bonris found longneck tracks next to Sharp Claw's tracks and tries to across the river and meets a club tailed longneck (Shunosaurus) named Shuno (Richard Ian Cox) who helps them across.
Later as Littlefoot knows how he has brother and sister, Longin and Linga told him that his father Bron adoptive them a long time ago and they welcome him to the land of the longnecks that they left to meet up with him and they're the leader of a huge herd and plans for a longneck ceremony for Littlefoot to bring honor for his siblings.
Meanwhile, the gang and the longnecks finally found Sharp Claw and his pack and tries to stop them before heading for the longnecks.
Later, the longnecks begin the longneck ceremony where Amargus, Alama, and Argent have past and Littlefoot was next to bring honor for his siblings as he face off against a strong longneck (Zigonosaurus) and won and has brought honor for all longnecks as a real longneck.
At the floating fire land, Chomper and the gang stops Sharp Claw and his pack from trying to reach the longnecks and Sharp Claw was surprised to see Chomper again and attacks him and Chomper caused his right claw to get burn by a fire on a stick in the floating fire (lava) and he and the others took out half of his pack as the land starts erupting and was able to escape, and Sharp Claw who's badly burn continues to move on along with his pack and Chomper and the gang have to stop him.
Later, Littlefoot knows that his brother and sister are almost ready to be the Alpha and Beta tomorrow when they do one final text.
Later at night, Littlefoot was thinking if he wants his siblings to come to the Great Valley with him or stay with them, and in the morning at dawn he sees Sharp Claw and his pack coming towards him along with Two crest headed sharptooth (Yangchuanosaurus) but had help from his friends who finally came and Chomper still has to settle a score with Sharp Claw so he doesn't hunt others anymore and then Littlefoot's brother came to the rescue and Cera was shocked that Littlefoot has another brother and then another sharptooth called a long mouth sharptooth (Qianzhousaurus) arrived and the same sharptooth Chomper and the others encountered arrived and the fight begins and Shuno and Bonris came to help them and Littlefoot helps his brother and Chomper deal with Sharp Claw while his sister along with Amargus, Alama and Argent help out and then Zigono arrived to help fight off the sharpteeth and the sharpteeth retreated and all of Sharp Claw's pack also retreat and Sharp Claw was about to attack Chomper,but Chomper moved from being attack and scratched him in the face before Littlefoot hit him with his tail to the wall where a huge rock fall on him causing him to his death and Chomper was surprised to put an end to Sharp Claw for good with the help from Littlefoot and his siblings, and Longela and Lonsha nows makes Longin and Linga the alpha and beta longnecks for protecting the herd with Littlefoot and his friends' helps and the gang was surprised to meet Littlefoot's new family members and Littlefoot wants their siblings to home with him, but his sibling can't cause they have to lead their own herd to a new home and Longela told Littlefoot the reason he brought him to them was to help them past many trials for them to become the alpha and beta longnecks like Shorty did and then Littlefoot says goodbye to his siblings and the gang say goodbye to their longneck friends as they are welcome to Longin and Linga's herd and they also say goodbye to Longela and Lonsha and their herd as they set off to their home and the Littlefoot and the gang head on home.
As they return to the Great Valley, Mr.Thicknose was surprised that Littlefoot has an adopted brother and sister that are alpha and beta and one day he will see them again.
Felix Avitia as Young Littlefoot
Jason Raize as Shorty
Elizabeth Daily as Young Shorty
Kiefer Sutherland as Bron
Barry Bostwick as Grandpa Longneck
Miriam Flynn as Grandma Longneck
Special Guest Stars
Bill Switzer as Longin
Danielle Panabaker as Linga
Dee Jay Daniels as Amargus
Kelly Vitz as Alama
Drake as Argent
Michael Angarano as Bonris
Richard Ian Cox as Shuno
Giancarlo Esposito as Longela
Lupita Nyong' O as Lonsha
Gititan Ian James Corlett
Laz Alonso as Ven Tey
Winston Duke as Zigono
Andy Serkis as Sharp Claw