The first half of the book covers the data structures used in solving the network problems that are presented in the second half. These data structures including disjoint sets, heaps, and search trees. Highlights of this half of the book are Tarjan's proof of the amoritized cost of union find, and explaination of self-adjusting binary trees.
The second half of the book covers four classical network problems: minimum spanning tree, shortest paths, network flows (e.g. min-cut), and matchings.