# Dragon Ball Z, Vol. 4
## Part I: The Saiyan Threat
- Arrival of the Saiyans
- Raditz's arrival on Earth
- Introduction of Goku's brother, Raditz
- Raditz reveals Goku's Saiyan heritage
- The Battle with Raditz
- Goku and Piccolo team up to fight Raditz
- Sacrifice of Goku to defeat Raditz
- Raditz's prediction of more powerful Saiyans arriving
## Part II: Preparation for the Saiyan Invasion
- Training Begins
- Gohan's introduction to martial arts
- Piccolo takes Gohan under his wing for training
- Goku's journey to King Kai's planet for advanced training
- Power Levels and Transformations
- Understanding power levels and their significance
- Goku's training under King Kai
- Techniques learned on King Kai's planet (e.g., Kaio-ken)
## Part III: The Arrival of Vegeta and Nappa
- The Saiyans Arrive
- Vegeta and Nappa land on Earth
- The destruction of East City by Nappa and Vegeta
- The Z Fighters gather to face the Saiyans
- The Battle Begins
- Initial skirmishes between the Z Fighters and the Saiyans
- Yamcha, Tien, and Chiaotzu's sacrifices
- Piccolo's ultimate sacrifice to save Gohan
## Part IV: The Climax of the Battle
- Goku's Return
- Goku arrives at the battlefield after intense training
- Goku faces off against Nappa
- Goku defeats Nappa with the help of his new techniques
- Vegeta Takes the Stage
- Vegeta's overwhelming power compared to the Z Fighters
- Goku's battle with Vegeta begins
- Use of the Spirit Bomb against Vegeta
## Part V: The Aftermath
- Vegeta's Defeat
- Vegeta's near-death experience and retreat
- Krillin and Gohan's attempt to finish off Vegeta
- Yajirobe's intervention with the sword to injure Vegeta
- Future Threats
- Vegeta's vow for revenge
- The foreshadowing of the Namek Saga
- Goku's recovery and preparation for future battles