Storywise, the action takes place around the same time as the book of Ezra: Artaxerxes is still king, many Jews are either in captivity or dead, and Jerusalem is a smoldering ruin (which is odd, as we saw in Ezra that Artaxerxes already sent him over there to rebuild the temple of god. It's like parallel history - competing versions of "the truth"). Nehemiah works as a cupbearer for king Artaxerxes (a job with a lot of responsibility, I gather, in a time where servants constantly conspire to kill their ruler). When noticing his gloomy demeanor, the king asks what's the matter. Nehemiah explains about the plight of Jerusalem and the Jewish people and asks for permission to travel there to rebuild the city & assist the Jews. The king gives him full permission, including royal letters for artisans and building materials like timber. Nehemiah travels to Jerusalem, and with the help of some returned Jews the city is painstakingly repaired, starting with a solid city wall (all houses have also been destroyed). The "enemies of Jerusalem" (Samarians, Arabs & such), upon hearing about the rebuilding, vow to attack & demolish the city. This makes rebuilding a rather grim (and highly impractical & slow, I might add) process, as all workers have to work single-handedly - with the other hand they need to hold a weapon at all times for fear of a sudden attack. Nehemiah berates his people for usury and urges them to return all stolen goods immediately to their rightful owners - the Jews. The people, who at first complain about the loss of revenue, immediately change their mind and gladly comply. (It's worth pointing out here that Nehemiah himself is not a Jew, but just concerned for the well-being of these "god-chosen" people. A noble and almost christ-like figure, it seems; although he kinda spoils it by piously demanding credit from god for all the good he did for the Jews.) When the building of the wall nears its completion, the enemy leaders (Sanballat of Samaria, Tobiah and Geshem the Arabian) try to entice Nehemiah out of the (well-defended) city for a "meeting", where they intend to capture & kill him. Nehemiah, rightfully smelling all kinds of small rodents, kindly declines the invitation, and swiftly finishes work on the walls by adding large (and heavily guarded) city gates. Tobiah continues to send threatening letters (evil!).
A census is held to determine how many people live in the city by now. From a (no doubt well-meaning but extremely boring) list of names & numbers (families, genealogies and even animals) we learn that there are actually not that many Jews living in Jerusalem at the moment - but then, these are the only survivors to return from captivity by Nebuchadnezzar, all those years ago. (And obviously, while we're busy stocktaking, we might just as well make an additional list of valuables such as gold, right? And it's self-evident that all this gold should go to the priests, because they are after all our connection to god, right? Right, say all the people and gladly hand over their wealth. Oh, the timelessness of it all.)
At a public meeting, the "book of the laws of Moses" is fetched and recited. The people weep (no wonder, it's so full of bullshit rules and prohibitions) but are determined to live up to the rules from now on. During a cleansing ceremony, they address god and give a recap in prayer form of all the great things he did for his people so far (he presumably remembers, so it's a tad superfluous… but then, these were all stories in oral circulation for hundreds of years - no wonder they turn up in some form or other, time and again). By the by, god keeps strangely silent all through the book, not once betraying his presence. It seems that just believing in him is sufficient, he doesn't even have to be there (or exist…) for good people to do stupid or ugly things (there is a lesson here). The people, aware of the many transgressions of their forebears, resolve to write a new "covenant" to renew the contract with god, so to speak, promising future good behaviour. All is duly set up, written down and signed. They even add a couple of new laws/rules about division of work, taxes, families & such, solemny promising never again to "forsake the house of our god". A laudable effort, no doubt, but my cynical self already wonders how long this latest delusion will last (usually, it's about one generation, tops). It's a bit like new year's resolutions - they're fine for about a week, after which they are discreetly discarded.
Seeing that they are a bit low in numbers, a repopulation program is instigated: one tenth of the Jews is to remain in Jerusalem, the others will spread out all over Israel to repopulate other afflicted cities (and as we know these guys breed like rabbits, filling up the country shouldn't take them too long).
Beautiful, utopian and noble - right? Sadly, as always, it's too good to be true, and once more we find the venom is in the tail. After reading in Moses' book about those pesky Ammonites and Moabites (who, as Moses warns, should never "come into the congregation of god" because they worship evil - or at any rate, other - gods), they "separated from Israel all the mixed multitude". In other words: racial segregation, discrimination and ethnic purification, once again. I am sad but not surprised. Foreign visitors are kicked out, their food thrown out of the windows, and itinerant merchants are penalized for trading on the sabbat. Some children from mixed marriages, who speak a foreign tongue, are even cursed, smitten (beaten) and have their hair torn out (yes, children) by our hero Nehemiah, who predictably turns out to be a nasty asshole after all (so far for the "good guys"). He forbids the children to marry "our" daughters (and he's not even Jewish himself!), diluting the pure blood, in a blatant "noble us vs. evil them" hate speech, before piously concluding that god "remember him for good" for "cleansing them from all strangers".
Once more, may I remind you that in the bible, "shalom" (holy peace) simply means: the complete absence, subjugation or even extermination of all undesired individuals, thereby establishing a "pure" and peaceful society - under the sadistic rule of a rabid dictator, who imposes thousands of nonsensical laws on his people. Now are you still angry at me for comparing the bible to Mein Kampf?