Katherine and her husband Christopher were on a trip to the Western American coast with their two sons Scott (Cyclops) and Alexander (Havok). Unbeknown to them she was also pregnant with their third son Gabriel (Vulcan). There plane was attacked by the alien race known as the Shi'ar. The Shi'ar craft fired on the Summers' plane, which was constructed heavily out of wood, causing it to burst into flame. Unable to find more than one usable parachute in time, Katherine Anne put it on her eldest son Scott, told him to hold onto Alex, and pushed them both out the plane door, hoping to save them both. Scott and Alex thus escaped the Shi'ar.
Katherine and her husband were not so lucky and were taken prisoner by the Shi'ar where they were separated on the Throneworld of Chandilar. It is unknown where her husband is taken, but Katherine is taken by the Shi'ar Emperor D'Ken who tries to force himself on her. When this happens Christopher interrupts them and tries to save his wife. The Emperor is so angry at him and kills Katherine right there in front of him in cold blood.
Very little is known about the mother of the three Summers children.