In this novel and mini-series, a foreign-born financier comes to London; and while he wants a way in to the upper class (which isn't about money but breeding), they all want to get on his good side since he's got all the money and the plans to make more money. As typical in Trollope (I can say, having read one novel and this TV Tropes article on him), there are several plotlines, lots of stories of love that is blocked for some reason (religious difference, previous engagement, lack of money).
It's almost a shame that this mini-series isn't being made now (perhaps as a counterpoint to Downton Abbey?), since the issues of financial crime seem newly pertinent. It's no surprise that things don't turn out well in the novel--Trollope likes rewarding his heroes and punishing his victims. What's surprising is that the scheming financier Augustus Melmotte evokes any pity from us at all: unlike the greedy British peers who he's trying to join, Melmotte actually seems to understand the violence and sacrifice underpinning his money.
So when Melmotte loses everything and is punished, well, on one hand, this is no more than the game he played and the chance he took; but at least he's punished, while many of the British peers go on about their narrow lives, unpunished and unenlightened.
But then I might be thinking of this mini-series wistfully since the cruel bankers are crushed instead of receiving bailouts that they don't even acknowledge. (For more on that, listen to this interview of bankers saying that they're smarter and that's why they're employed and wealthy.)