After learning of his son’s death in a mission aboard the Enterprise, Michael Fuller reenlists as a security officer and ends up aboard the Enterprise himself. At that time, the Enterprise was being refitted with enhanced weapons and other upgrades at Starbase 56, in anticipation of possible problems with the Klingons. It then gets called to return to System 7348 (where the Enterprise had fought Orion miners working for the Klingons), because a Klingon delegation is being allowed inside Federation space to conduct negotiations with the proto-Klingon inhabitants of the planet. When it is learned that the Klingons are sending a warship, rather than the agreed civilian vessel, the Enterprise has to leave the starbase in a hurry to try to get to System 7348 ahead of the Klingons. Before they get underway, Lieutenant Parrish discovers she is pregnant, and the father of the expected child is the late Jon Anderson (as he was known), who had been a Klingon infiltrator named Kell. The Klingon ship is the D’k Tahg, captained by Koloth with first officer Karel. Karel is the brother of the late Kell, and he had got his new position after the previous first officer had made a fatal challenge against the captain. The D’k Tahg is also transporting Councilor Duras and a contingent of troops loyal to him, and Captain Koloth and Karel both distrust Duras’s motive, and doubt his honor. En route to System 7348, events cause Fuller to recall the memory of the battle against the Klingons at Donatu V in 2242, which is an event that the Klingons want to get revenge for. [Timeline: year 2267]