Complex sentence: Crichton quickly comes up with a plan to get rid of the Grudeks and, with everybody's help, they succeed, and then go off in Elack in search of D'Argo and Jool.
Split into simpler sentences: Crichton quickly comes up with a plan to get rid of the Grudeks and, with everybody's help, they succeed. They then head off in Elack in search of D'Argo and Jool.