Injured on a junkyard planet in the 67th century, the TARDIS team wakes up on an emergency medical freighter in deep space. Also on board are a pregnant man named Yoss, who is grappling with giving his baby up for adoption, and decorated pilot Eve Cicero, whose android companion Ronan has been helping her hide the truth about her health from her brother Durkas. The ship's shields are soon penetrated by a Pting, a nigh-invulnerable creature capable of devouring any form of inorganic matter. As the Pting rampages through the freighter, only the Doctor and her friends can save the passengers from destruction.