The rising action of The Big Friendly Giant is when the giant takes Sophie into the cave. She is afraid that she is going to be eaten by the giant. This is the rising action because it is the part of the story that leads up to the climax of the story, which is when the BFG had to hide her in his mouth to prevent her from being found by other giants.
The rising action of a plot involves the creation of the major conflicts or "problems" in the narrative of a literary work. These conflicts are that which impede the protagonist from accomplishing what he or she sets out to do. In Roald Dahl's story of a benevolent giant who infuses children's heads with pleasant dreams, a little orphan awakens in the night at the "witching hour" and sees this giant cloaked in black and blowing something into the window above her at the orphanage where she lives, and several problems develop as a consequence to this sighting.
Because Sophie has spotted this giant with monstrous ears and a wrinkled face, he captures her and whisks her away to his cave. This act is the initiation of the rising action; however, it is not his taking of Sophie that is the most frightening and dangerous part of the narrative. Rather, it is the fact that she has seen him and would alert the media about giants if he were to not to have removed her from her society. For, if Sophie were to alert the media, the authorities would conduct a search for these giants if, in fact, they believed Sophie.
"So what will happen to me now?"
"You will just have to stay here with me for the rest of your life."
Then, what becomes more problematic is the fact that Sophie lives with him and the BFG must protect her from the man-eating giants who live in the same area where the kind giant dwells. The other giants' intrusion in their lives is the greatest obstacle to the lives of both Sophie and the BFG and the largest part of the rising action of Dahl's novel as it introduces the main conflict. Explaining to Sophie what the giants would do if they see her, the giant remarks,
"You would be swalloped up like a piece of frumpkin pie, all in one drollop!"
Appalled by this eating behavior of the other giants, Sophie asks if there is nothing that can be done about them.
So, after several close encounters with death in the conflicts with the cruel giants, the BFG and Sophie decide to enlist the help of the Queen of England in ridding the country of these evil creatures.