"Percy Jackson & the Olympians: The Lightning Thief" is an action-adventure movie set in the 21st century. The movie is about a teenage boy named Percy Jackson who discovers he is a descendant of Poseidon, the Greek god of water, and, as such, is a demi-god with certain water-related supernatural abilities. The film is based on the popular children's fantasy novel of the same name. The film's director is Chris Columbus, who directed two of the "Harry Potter" films.
"Percy Jackson & the Olympians: The Lightning Thief" opens with a conversation between Zeus and his brother, Poseidon, overlooking modern-day New York City; Zeus is explaining to Poseidon that his lightning bolt has been stolen, and he blames Poseidon. Poseidon tries to explain he does not have the lightning bolt, but Zeus tells him if the lightning bolt is not returned by a certain deadline, he will wage war on Poseidon. The scene cuts to Percy, who is sitting underwater in a school swimming pool. When the boy surfaces, his friend, Grover, exclaims that he had stayed submerged for almost seven minutes. Percy and Grover go to their next class to find that they have a substitute teacher named Mrs. Dobbs.
The next day, there is a school field trip to a Greek exhibit at the museum. Mr. Brunner, another teacher at the school, and the substitute Mrs. Dobbs chaperone the trip. While Mr. Brunner explains to class about demi-gods, Mrs. Dobbs asks to speak to Percy alone. She leads him to an unfinished room in the museum and asks, "Where is it?" Percy appears confused. Mrs. Dobbs changes into a winged creature -- a "fury" -- and attacks Percy. At this point, Grover and Mr. Brunner burst in. Brunner demands the fury let go of Percy. The fury obeys, then leaves by crashing through the window.
Mr. Brunner explains to Percy that he is the son of Poseidon. Brunner explains to Percy that he is no longer safe, and Percy should go to a special camp, "Camp Half Blood," that is just for the descendants of the gods. On the way to the camp, Percy is attacked by a monster. He narrowly defeats the monster, then faints afterward. Percy awakes in the camp, where Grover and Brunner explain the origins of his birth and why he is being attacked. At the camp, Percy takes part in battle training and other exercises designed to develop his natural talents.
After Percy wins a mock battle, there is a huge feast. In the midst of the celebrations, Hades, the god of the underworld and the brother of Zeus and Poseidon, appears. He tells Percy that he has Percy's mother, Sally, captive and he will not release her until Percy gives him Zeus's lightning bolt. However, Percy doesn't have the lightning bolt, so he, Grover and a girl from camp, Annabeth, set out on a journey to find it. After many trials, the three adventurers still have not found the lightning bolt, so they go to Hades in the underworld to negotiate Sally's release. A battle ensues, during which the lightning bolt is discovered in one of Hades' relics. Persephone, Hades's prisoner and assumed wife, zaps Hades, giving Percy, Annabeth and Sally time to escape. Grover stays to serve Persephone.
When Percy, Annabeth and Sally emerge from the underworld, they expect to be in Olympus but instead find themselves on the top of the Empire State Building, where Sally explains that the building contains a secret entrance to Olympus. Zeus' deadline is just minutes away, and they are trying to get to him before the deadline to demonstrate that Poseidon had not stolen the lightning bolt. A young demi-god from the camp, Luke, appears. He explains that he set everything up so Percy would be duped into taking on the role of messenger of the gods. Percy and Luke fight. Percy eventually wins and casts Luke into the river. Percy and Annabeth make their way to Olympus; however, Sally has to stay behind because she is mortal. Percy and Annabeth deliver the lightning bolt to Zeus just in time. Percy explains all that had happened. Zeus listens to the boy, then proclaims peace.