Jhereg is the first book in the fantasy series about Vlad Taltos, a marvelously snarky yet quite competent assassin. Vlad lives in the city of Adrilankha, capital of the Dragaeran Empire, an Easterner (human) among the many families of the Dragaerans (elves). Easterners have always been despised, even when they're not being systematically exterminated by the Dragaerans, but Vlad's father purchased a baronetcy for himself and his family, which has allowed him some status, at least in the clan of the Jhereg - an organized crime clan that lets mixed races and even the occasional human join.
Jhereg actually jumps in at the middle of Vlad's story, and subsequent volumes in the saga are occasionally flashbacks to earlier snippets, but what little we don't understand at first is either explained sufficiently by Brust or left as a niggling little question to pique our interest in Vlad's further adventures. At this point, Vlad has responsibility for a certain amount of territory with the Jhereg, and acts as a mid level boss, overseeing gambling, prostitution, and other criminal activities - and very seldom has to do assassinations any more.
However, one of the members of the Council of the Jhereg, Mellar, has absconded with $9 million in gold from the treasury, and it is imperative that he be killed and the gold recovered quietly. Vlad is approached by another council member, The Demon, to arrange for "a friend" to take care of the matter. It's really an offer he can't refuse, and the fee is quite generous, so he decides to take on the hit.
To complicate matters, Mellar has fled to the sanctuary of Castle Black, the floating domain of Lord Morrolan, of the Dragon clan, for whom Vlad moonlights as a security consultant (the beginning of their friendship is found in another Brust novel). Morrolan's honor requires that if a guest in his home is harmed, they must be avenged. The last time a Jhereg was assassinated in a Dragon's home, it led to a war between the clans that nearly destroyed both of them.
This is, of course, an undesirable outcome for Vlad and his friends, so he has to find a creative way to get Mellar to leave of his own will, so he can be killed. In the process, Vlad will learn a great deal about himself, a few things about his friends, and we'll get to learn right along with him about the fun fantasy world Brust has created.
Jhereg is a delightful yarn, with a mystery at its core, which will probably get you hooked on the rest of Vlad Taltos' story.