When the SG-1 team stumbles upon the chamber of former Goa'uld enemy Ma'chello, they fall victim to his powerful body-swapping invention. Ma'chello takes on Daniel's body and the young archeologist finds himself trapped in the body of an old and dying man.

During a routine reconnaissance mission, the UAV plane crashes into a cactus-like plant. Sent to recover the plane, SG-1 discovers that the inhabitants have begun falling ill, and before long a plague of illness sweeps the race.