Sophie (Amanda Root) is a young orphaned girl living in the orphanage of the cantankerous and abusive Mrs. Clonkers (Myfanwy Talog). One night, Sophie wakes up and goes to look through the window but sees a cloaked giant blowing something through a trumpet into a bedroom window down the street; whereupon the giant notices her and snatches her to the realm of Giant Country.In his cave, the giant identifies himself as the Big Friendly Giant (David Jason) who blows dreams into the bedrooms of children at night, while all the other 9 giants are vicious, child-eating beasts. Because the BFG refuses to eat people or steal food from humans, he subsists on a revolting vegetable known as a "Snozzcumber", which is all that grows in Giant Country. He explains that he took her so she couldn't tell anyone that she had seen him and start a giant hunt. Sophie and the BFG quickly become friends; but Sophie is soon put in danger by the sudden arrival of the Bloodbottler Giant (Don Henderson), who suspects the BFG of harboring a human after hearing him talking. The BFG tricks the Bloodbottler into eating the Snozzcumber to repel him from his cave, during which Sophie is almost eaten. The BFG makes her a new dress out of her blanket to replace her ruined nightgown while she has a bath. When Sophie announces she is thirsty, the BFG treats her to a delicious fizzy drink called "Frobscottle", whose bubbles go downwards, which causes the drinker to fart; this is known as a "whizzpopper" to giants, and causes the drinker to soar and shoot around the place.The next morning, the BFG takes Sophie to Dream Country to catch more dreams, but they are first tormented by the other giants along the way; notably by the Fleshlumpeater Giant (Don Henderson), who is the largest and most fearsome and hideous. In Dream Country, the BFG demonstrates his dream-catching skills to Sophie and teaches her to fly; but the BFG mistakenly captures the worst kind of nightmare. Upon arriving at his Dream Cave, the BFG shows Sophie all the dreams he has captured already and locks away the nightmare in his cavern of lava in a tiny chest, and takes Sophie to watch him on his dream-blowing duties; but this is cut short when they spot the Fleshlumpeater eating a little boy whom the BFG had previously given a pleasant dream. When Sophie tries to intervene, the BFG flees with her and escapes to save her from the Fleshlumpeater. Afterwards, the grief-stricken Sophie tries to persuade the BFG to stop the evil giants.At first, the BFG is reluctant to do so out of cowardliness and low trust in humans; but Sophie develops a plan to expose the evil giants to the Queen of the United Kingdom (Angela Thorne). Using dreams from his collection, the BFG creates a nightmare, blows it into the Queen's bedroom, leaves Sophie on the Queen's windowsill to confirm the dream and retreats into the palace gardens when Sophie calls him. Because the dream included foreknowledge of Sophie's presence, the Queen believes her story, and speaks with the BFG. After considerable effort by the palace staff, the BFG is given a copious breakfast.Once ready, the British Army and the Royal Air Force, in a fleet of RAF Chinook helicopters, follow the BFG to Giant Country to the 9 giants' homeland, where the giants are tied up and taken prisoner. The only one isn't there is the Fleshlumpeater, who immediately attacks the BFG for his betrayal and later pursues Sophie when she intervenes; but after a long chase he is stopped when the BFG kills him with the nightmare he had captured earlier, which he later reveals was a nightmare about Jack and his beanstalk, both of which all giants, including the BFG himself, fear.The tethered giants are then all transported by the helicopters to London, where they are imprisoned in a deep metal pit and forced to eat Snozzcumbers for the rest of their lives. The orphanage is closed down so the children move into the palace and Mrs. Clonkers is given the job of feeding giants. Contrary to the book's ending, the BFG stays in Giant Country instead of moving to England, and Sophie becomes his assistant at the distribution of dreams and people think they will visit Buckingham Palace sometimes.