Here's what happens:
* Drevin is a Russian arms dealer and Alex Rider is tasked with infiltrating his organization. Alex is initially sent to a boarding school to befriend Drevin's son, but eventually, he is sent undercover to Drevin's operation.
* Drevin plans to unleash a deadly virus on the world. He has created a biological weapon called "Ark Angel" and plans to release it in a major city.
* The CIA learns of Drevin's plans and tries to stop him. They send agents to track down Drevin and his weapon.
* Alex and the CIA agent, Jack Starbright, are caught in a confrontation with Drevin. Alex and Jack are trying to stop Drevin from unleashing the virus.
* Drevin is killed by the CIA. In a desperate attempt to save himself and Alex, Jack activates a bomb that was planted in Drevin's safe room. The bomb explodes, killing Drevin.
It's important to note that Alex Rider does not directly kill Drevin. He is simply present when Drevin is killed by the CIA bomb. This highlights the themes of the novel, which explore the complexities of espionage and the moral gray areas of fighting for what is right.