Athens is Saved! opens with a note To the Reader from the author. The note explains that the story is based on a real event, with some invented parts added to make the story more fun. The author adds his wish that the story will encourage the reader to find out more about ancient Greece and perhaps to run their first marathon.
Notes on The Story So Far are divided into three sections: Ancient Greece, The Persians, and Athens. Ancient Greece explains that "Before the time of Jesus Christ" (p. 8), Greece was one of the most rich and interesting places in the world. It was divided into city-states, there was a shared language and shared gods. Most Greeks were farmers but slaves did most of the hard work. Some Greeks were merchants. All fit men had to be ready to fight in war. The Persians explains that Persia is the 'old name for Iran'. It had a huge empire from India to Europe and Darius I wished to make it even bigger. Athens describes the acropolis and the city's walls. Being near the sea made it a base for merchants. It was a city of wealth and ideas, full of poets, thinkers, and writers, with an unusual system of letting all citizens have a say in the running of the city. The citizens are training for war now that they have heard of the threat of Persian invasion.
A timeline follows. One page has "BC (Before the birth of Jesus Christ)", the facing page has "AD (After the birth of Jesus Christ)". The timeline goes from 800BCE–1900CE. The first section features events such as the first Olympics, first written laws in Athens, foundation of Persian Empire, alliance of Athens and Plataea, Athens helping the Ionians, 1st and 2nd Persian invasions. The CE section features the abolition of the Olympic Games in 393 and the first modern Olympics in 1896.
A Portrait Gallery features pencil drawings of the busts of the six main characters: Cimon a young athlete; Naxi, Cimon's slave; Paros the bully; Callimachus the commander-in-chief; General Miltiades; and General Nicias. Miltiades is shown with a Corinthian helmet pushed up onto his forehead.
The story begins in the training ground of Athens. Young men there are preparing to run a race overseen by Callimachus. Cimon is a gifted runner, but he is being bullied by the others, particularly, Paros, and they mock him for his stammer. He is tripped by Paros during the race and Callimachus scorns him as a clumsy fool. Cimon shows his dedication by returning to the training ground the following morning for weapons training. It is explained that the Greeks are spear-wielding foot-soldiers who must fight close together to see off Persian cavalry – the best in the world. News arrives that the Persians have landed. Paros continues to taunt him, but Cimon attends the Assembly and hears Miltiades arguing that the Athenians will be able to withstand the Persian cavalry and that they are likely to be backed up by the Plataeans and Spartans. Miltiades wins the argument. The army will be mustered. Philippides the runner will go to Sparta for help. Cimon returns home to prepare for battle but wishes he were going in place of Philippides – we later learn that he dreams of being a messenger.
The Athenian army sets out for Marathon. Many of the men are soon tired by the pace set over the challenging terrain. Miltiades notes that Cimon is still in excellent condition and makes a note of his name. Paros taunts Cimon once again, but when Cimon goes to retaliate another soldier holds him back and notes that Paros is only doing it because he is struggling and envious. When the army stops at a rest point, Cimon goes forward to view the Persian army. He meets Miltiades there. Miltiades asks him if they can win and when Cimon insists that they can, Miltiades approves.
The Athenians halt at Marathon in a grove sacred to Hercules. The generals meet. Miltiades wishes to establish a plan so that they can fight as soon as possible. General Nicias accuses him of rashness and insists that they will be cut down if they rush out to fight. Miltiades outlines a plan. The generals are split and Miltiades speaks privately to Callimachus who has the deciding vote. He urges him that if they go ahead, Athens will win its freedom and become the greatest city in Greece. Callimachus agrees, and five of the generals give their command days up to Miltiades. Cimon and Paros are told that their unit will fight in the centre of the battle line. News arrives; the Plataeans are on their way but the Spartans are held up by a religious festival. The Greeks are outnumbered 25,000:10,000.
As they prepare for battle, Paros approaches Cimon and apologises sincerely for bullying him. He explains that he has been envious of Cimon's greater athletic ability. They agree to put the past behind them to concentrate on the real enemy – the Persians. Callimachus is annoyed to see Cimon in the centre and raises an objection with Miltiades citing Cimon's clumsiness. Paros intercedes and confesses to having tripped Cimon. Cimon then protects Paros from Callimachus' disapproval by laughing it off. Later, the two young men stand guard and hear people approaching the Greek camp. After a tense few moments it is revealed that Ionian Greeks compelled to fight in the Persian army have come to give the Greeks a warning. They explain that the Persians are removing their cavalry, creating the perfect opportunity to attack. Paros and General Nicias are suspicious, but Cimon and General Miltiades trust the Ionians. Callimachus consults a priest about whether or not it is a good day to fight. The priest says that it is, although Callimachus decides to sacrifice anyway to "be on the safe side" (p. 32).
The day of battle arrives. The Greeks push forward behind a barricade, drop the barricade, and then rush forward. The Ionians are proved to have been true to their word and no cavalry appears. The fighting in the centre is very fierce. Cimon realises that they are losing, but he and Paros hold firm, fighting side by side and persisting despite their wounds. Cimon realises that they must regroup and bids Paros use his clear voice to call the men to him. The centre holds. After a desperate struggle Cimon realises that the Persians are retreating and those approaching their band of survivors are Greeks. Many Persians have been killed and far fewer Greeks, although that did include Callimachus. Miltiades explains to Cimon that he deliberately left the centre light on men, with the best men there, to give the wings a better chance of winning and then encircling to relieve the centre. Miltiades roars that Athens owes everything to Cimon and Paros. He asks them what they would like as a reward. Although wounded, Cimon begs for the honour of returning to Athens with the message of their victory. Miltiades grants his wish. Cimon struggles in a heroic run to Athens, delivers his message, and dies as people declare "Athens is saved!" (p. 38).
The History File. This section follows the main narrative and provides further historical context. After the Battle describes the second invasion and its defeat and the Spartans' victory in a follow-up war between Sparta and Athens. The Olympic Games outlines the importance of sport in ancient Greece and the competitions held at the games. It goes on to say that Pierre de Coubertin established the modern Olympic Games so that people could compete in sport rather than on the battlefield. Some of the adoptions from the ancient Olympics are outlined. The Modern Marathon explains that the modern Olympic Committee wanted a long distance race and decided to base it on the story of the runner who sped from Marathon to Athens. The idea caught on and there are now many marathon races. How Do We Know? is an introduction to ancient Greek source material. Herodotus and Plutarch are both discussed. The tangled traditions of the first marathon are unteased. It is explained that Herodotus mentioned Philippides (or Pheidippides) running to Sparta, but did not refer to a run to Athens. Plutarch did mention the run to Athens, but wrote much later and may therefore be less reliable. English poet Robert Browning "muddled things up even more" (p. 43) by writing about Philippides running to Sparta, to Marathon, and back to Athens where he died of exhaustion. It is concluded that we may never know for sure what happened. The author then explains that he chose the Plutarchan story because that run is the origin of the modern Marathon. He reiterates that elements of the story are made up, but that Miltiades' plan, the Ionians, and the battle are all real historical events. He adds that while Herodotus is difficult to read, children may enjoy reading more books about ancient Greece that they will find in libraries. A glossary of new terms concludes the work.