Anthills of the Savannah takes place in the imaginary West African country of Kangan, where a Sandhurst-trained officer, identified only as Sam and known as "His Excellency", has taken power following a military coup. Achebe describes the political situation through the experiences of three friends: Chris Oriko, the government's Commissioner for Information; Beatrice Okoh, an official in the Ministry of Finance and girlfriend of Chris; and Ikem Osodi, a newspaper editor critical of the regime.
Other characters include Elewa, Ikem's girlfriend and Major "Samsonite" Ossai, a military official known for stapling hands with a Samsonite stapler. Tensions escalate through the novel, culminating in the assassination of Ikem by the regime, the toppling and death of Sam and finally the murder of Chris. The book ends with a non-traditional naming ceremony for Elewa and Ikem's month-old daughter, organized by Beatrice.