Following events of Scorpia, Alex Rider is in a hospital recovering from an assassination attempt. Four masked men come to the hospital attempting to kidnap Paul Drevin, the son of Russian billionaire Nikolei Drevin, who is financing a revolutionary space hotel named "Ark Angel". Alex fights the men, in an attempt to save Paul, he pretends to be Paul. He knocks all four of them out, but then a fifth man comes in to the hospital and overpowers Alex. Still weak, Alex faints and is kidnapped.
Alex is taken to a flat in a building site, where he finds out the men belong to Force Three, an eco-terrorist group led by a man named Kaspar. Despite proving he is not Paul Drevin, Force Three lock Alex up and set fire to the apartment, but Alex escapes and Nikolei Drevin invites him to come and stay for two weeks in the lap of luxury for saving his son and see an Ark Angel rocket take off. While at Drevin's home, Alex starts to befriend Paul, but decides to leave him and his father once they arrive in New York in route to Flamingo Bay, mainly due to the fact that Nikolei Drevin nearly killed him in a go-kart race.
On route to Flamingo Bay, Alex is taken with Paul and Nikolei Drevin to New York. At the airport, he is held up at customs and taken to the CIA. He is told that Nikolei Drevin could be "the biggest criminal in the world", and the CIA recruits him to gain information on Drevin. Upon his arrival at Flamingo Bay, Drevin learns of Alex's CIA connections and decides to have him killed while scuba diving. Alex becomes trapped in a sunken ship named the Mary Belle. With the help of Tamara Knight, an undercover CIA agent and who is Drevin's secretary, Alex escapes.
Alex and Tamara hide on the island, but are both captured. Drevin ties Alex up and then tells Alex that his rocket Gabriel 7 contains a bomb that will destroy Ark Angel, causing it to fall to Earth and destroy Washington, D.C. This will eradicate the evidence against him the CIA have accumulated in the Pentagon, as well as letting him reclaim some of his money spent on the (now regretted) Ark Angel project. Alex escapes using a CIA gadget from Tamara, and sails away from the island. Drevin tries to get away in a seaplane, but Alex causes Drevin to crash by tying two canoes to the plane, and Drevin is killed.
Drevin's rocket takes off before the CIA can stop it. Alex is then chosen to board a second rocket to move the bomb before it explodes, since he is the only one small enough to fit inside. When Alex arrives, he sees Kaspar and must fight him. Alex gains the upper hand when Kaspar is blinded by the sun's light, and then Kaspar is killed when he falls back on his own knife. Alex moves the bomb into the station's toilet and escapes. His escape capsule splashes down in the sea near Australia. The bomb explodes and the satellite falls harmlessly into the sea.