"Impossible Dream" (叶わぬ夢, Kanawanu Yume) is episode 27 of the Naruto: Shippūden anime.
Sakura is unable to heal her wounds as the sword in her torso is laced with poison, shutting her system down. Although she has been poisoned as well, albeit at a lesser degree, Chiyo uses the antidote on Sakura, causing the latter to regain her strength. Revealing another blade hidden in the joint of his puppet, Sasori detaches himself from the sword and takes a leap backwards, prompting to rush forward to finish off Sakura. Chiyo manages to block his move by stabbing him through his core using the "Father" and "Mother" puppets. With Sasori immobilised, Chiyo revives the nearly-dead Sakura using her reincarnation ninjutsu. Chiyo explains that the technique takes the user's life force and transfers it to another, reanimating them at the cost of the user's own life. However, because Sakura was not dead yet, Chiyo does not die from using the technique. Sasori wonders why Chiyo and Sakura would give their lives for one another, stating that he has no regard for human life himself, having claimed the lives of thousands of people. Chiyo places the blame of his mentality on the upbringing of those raised in Sunagakure, where shinobi are taught to only focus on themselves and not anybody else. At full strength once more, Sakura punches Sasori, but he tells her that he cannot feel pain, as he is a puppet, and wonders why Sakura and Chiyo tend to do pointless things. However, he decides to do something pointless as well, and as a reward for defeating them he reveals that he had a meeting with one of his spies, who works for Orochimaru, next week at the Tenchi Bridge in Kusagakure. He tells Sakura that he doesn't think he will make it to their rendez-vous, but dies before finishing his sentence. Sakura is glad that their battle is over, but Chiyo tells her that she was the one who should have died, explaining that Sasori was always able to read her movements, and therefore he knew her attack was coming, yet for some reason chose not to dodge her final attack.