The episode opens as Serenity heads to Ariel, a central world of the Union of Allied Planets as Inara is due for her annual Companion physical exam and license renewal. Following an incident in which River attacks Jayne he demands that she and Simon be left on Ariel. Mal quashes any talk of leaving people behind but privately warns Simon that River has to be kept under control. Simon acknowledges that his sister is getting worse.
Simon approaches the crew with a job: he wants to get into the hospital in Ariel's capital city in order to scan River's brain with an advanced piece of medical equipment, and he needs the crew to get him inside. As payment, the crew will be able to steal valuable medical supplies that they will be able to sell for a lot of money. Simon plans to drug himself and River so they appear dead, allowing the crew to enter Ariel city's hospital using a scrapped medical shuttle they refurbished and fake EMT IDs. The group would then split up, with Jayne guarding Simon as he analyses River's condition whilst Mal and Zoe steal drugs from the hospital.
The scheme starts off as planned and the team are admitted and Mal and Zoe head off to steal the drugs. Whilst waiting for Simon and River to wake up, Jayne makes a call to an Alliance officer who agrees to pay a reward for Simon and River. Once awakened, Simon dresses as a doctor and takes River to the diagnostic ward with Jayne. There, Simon discovers that River's brain has been surgically operated on many times, disabling her ability to suppress emotions.
With the analysis complete, Jayne leads them to a rear entrance where they are stopped by Federal marshals who arrest them. Jayne learns that the Alliance officer plans to arrest him for aiding and abetting the fugitive siblings, keeping the reward money for himself. Meanwhile Mal and Zoe return to the medical shuttle with the loot, but realize that Jayne and the Tams are late so head back into the hospital to find them.
The three prisoners are moved to a holding area where Jayne and Simon overpower their escorts and escape. Shortly afterwards two blue-gloved men arrive to take custody of the Tams, using a mysterious sonic device to kill all the marshals. Meanwhile, a terrified River leads Jayne and Simon to a locked door which is opened from the other side by Mal and Zoe and the group escapes.
Inara returns to Serenity just as the medical shuttle arrives. Once everyone else has left the cargo area, Mal knocks Jayne out. Jayne awakens to find himself in an open airlock as the ship begins to leave the atmosphere. Jayne eventually confesses that he betrayed Simon and River and Mal tells him that doing so was the same as betraying him. As Mal turns to leave, Jayne asks him not to tell his shipmates about the betrayal. Sensing repentance, Mal closes the outer door, sparing Jayne's life.