The final book in the Jihad line of sourcebooks. The first part of Final Reckoning covers the period from the fall of Terra in 3078 to the creation of the Republic of the Sphere in 3081. It does this the same way that the rest of the books have done, with various accounts strung together in chronological order. It ends with a complete timeline compiling all the previously published timelines into one section.
The next part is an overview of the Inner Sphere as of 3081, presented as an intelligence briefing for Devlin Stone, newly created Exarch of the Republic of the Sphere. This includes a rundown of known remaining Word of Blake forces.
Finally, there's the usual rules section at the back, the most notable being rules for designing super-heavy 'mechs of up to 200 tons.
Overall, a decent ending to the Jihad saga, spoiled only by the knowledge that the grand experiment being conducted by Devlin and his associates is ultimately doomed to failure with the coming Dark Age.