Mr. Link recruits explorer Sir Lionel Frost to help find his long-lost relatives in the fabled valley of Shangri-La. Along with adventurer Adelina Fortnight, this trio of explorers travel the world to help their new friend.
The charismatic Sir Lionel Frost (Hugh Jackman) considers himself to be the world's foremost investigator of myths and monsters. The trouble is none of his small-minded high-society peers seems to recognize this. Sir Lionel's last chance for acceptance by the adventuring elite rests on traveling to America's Pacific Northwest to prove the existence of a legendary creature. A living remnant of Man's primitive ancestry. The Missing Link (Zach Galifianakis).—LAIKA
In 1886, Sir Lionel Frost (Hugh Jackman), a struggling investigator of mythical creatures, has continuously searched for different creatures to study and announce their presence in the world, which would allow him to be accepted into a society of other "great men", which is led by Frost's rival Lord Piggot-Dunceby (Stephen Fry).
Mr. Lemuel Lint (David Walliams), is Sir Lionel's assistant who resigns after almost getting eaten by the Loch Ness Monster. Frost drew out the Loch Ness Monster by playing bagpipes in the middle of the lake and took a picture when the monster emerged from the water. Frost had to dive into the water to save Flint, which he manages to do, but the monster destroys their boat, and the camera due to which Frost had no proof of his discovery.
Frost receives a letter acknowledging the presence of a Sasquatch (along with a footprint), making a deal with Piggot-Dunceby that would allow him to join the society if he proved that the creature was real.Piggot secretly worries that the new age thinkers are challenging the established orders with ideas such as evolution and electricity and that he might not have a place in the new world. He considers it important to stop Frost from succeeding.
Frost travels from the UK to the Pacific Northwest via sea and railroad, eventually stumbling upon the Sasquatch in a forest. After dubbing him "Mr. Link," (Zach Galifianakis) Frost is told by the Sasquatch that he was in fact the one who sent the letter. Mr Link can speak perfect English and is quite civilized. Link is 8 feet tall, chest measuring 70 inches and weighing 630 pounds. Link says that he learned to read and speak by stealing books and newspapers. Link read about Frost from the papers.
Mr. Link requests Frost's help in finding his relatives, the Yetis, in the Himalayas. Link says that his world is getting smaller as humans expand their footprint. Plus, he is lonely as he is the last of his kind in the jungles.
Frost agrees to help him (in exchange for proof of Link's existence) but is unaware of the fact that Piggot-Dunceby has hired a bounty hunter named Willard Stenk (Timothy Olyphant) to track Frost and kill him, ensuring that he never ridicules the society again with his continuous searches. Piggot wants to make sure that the pro-imperialist conservative views of the society remain unchallenged.
Stenk corners Frost and Link at the local town bar, but Frost manages to defeat Stenk and escapes with Link.
Frost's old lover Adelina Fortnight (Zoe Saldana) has a map to the Himalayas locked in a safe that belonged to her late husband, one of Frost's past partners who died in the mountains of the Hindu Kush in an avalanche. Adelina lives in Santa Anna, California and Frost dresses Link in normal gentleman clothes for the journey. So, the two visit her mansion to acquire it. However, Adelina harbors resentment for Frost missing her husband's funeral and kicks him out when he offers to pay her for the map.
Frost and Mr. Link come back later at night and break in, but Mr. Link's noise making awakens Adelina, and the safe eventually falls out of the top floor window, cracking open in the aftermath. Frost and Mr. Link grab the map and escape but are discovered the next day by Fortnight who allows them to search for the Yetis as long as she is there to accompany them. Stenk arrives and a shootout ensues, but the trio trick their pursuer into hopping on the train to search for them.
The trio make their journey via boat, and Fortnight pressures Frost into reaching out to Mr. Link to prove his sincerity to reunite him with the yetis. Frost enjoys a heartwarming talk with Mr. Link on the boat's deck where Mr. Link gives himself the name "Susan", after a friendly prospector he once encountered. However, they are once again ambushed by Stenk. After various scuffles across different parts of the ship, the trio eventually locks Stenk in the boat's boarding rooms while they make another escape. Stenk keeps Piggot-Dunceby updated of the progress by telegram.
The trio eventually makes their way to the Himalayas and are pointed in the direction of the Yeti temple, and led to their Queen (Emma Thompson), who reveals their secluded valley to the group. She then reveals their disdain for mankind extends to Susan, who's interacted closely with them. They throw the trio in a pit for them to stay until they die. Susan gives Fortnight a boost and she knocks down a few Yeti guards, allowing them to stack them and escape. They run across the ice bridge, where an armed Piggot-Dunceby and Stenk are waiting at the center of the bridge. Frost denounces his rival's pride and defends Susan as more human than the society ever will be.
As a result, Piggot-Dunceby starts firing his rifle at the ice bridge, causing it to crack and break. Piggot-Dunceby and his assistant Mr. Collick (Matt Lucas) fall to their deaths while the trio and Stenk make a run for it. They are too late and are left hanging on the edge of the destroyed ice bridge. Stenk, who has made it all the way across, taunts Frost, which leads to the two engaging in a slapping fight while hanging on the bridge. The trio work together to rid themselves of Stenk, who falls to his death after an icicle breaks and falls on him. Frost appoints Susan as his new partner in investigations, who blows a raspberry at the Yeti leader.
After arriving home, Fortnight tells Frost that she will be adventuring on her own for a while and departs, but not before the pair share a brief mutual acceptance of their feelings for each other. Susan and Frost arrive back at the latter's work-space and begin their next case to find Atlantis. After they leave, the end credits reveal maps and souvenirs of their subsequent adventures.