Sheridan is shocked to learn that one of the crew of the Icarus, the ill-fated science ship that exploded with his wife aboard, is alive - namely Mr. Morden. Meanwhile, a representative from the newly established Ministry of Peace visits the station to recruit personnel to the Nightwatch.

When a fatal and contagious plague threatens the Markab race with extinction, Dr. Franklin races to find a cure before more of the station's residents are killed. However, his efforts are obstructed by the Markab themselves, who believe the plague only affects the immoral.