"Our Mutual Friend" is Charles Dickens
' next-to-last novel, completed in 1865. The Penguin Classics edition weighs in at a whopping 787 pages. It's one of Dickens' longest and most complex novels, containing three main plots, numerous subplots, and approximately 39 recurring characters.
If you don't want to know what happens, it's probably best to stop here.
It begins with the discovery of a body in the River Thames. The body is presumed to belong to John Harmon, who is the heir to an immense fortune. Harmon's father was a miser who grew rich as a dustman, and a condition of the will is that Harmon must marry Bella Wilfer, a girl he's never met, to collect it.
However, since Harmon Junior is presumed dead, the fortune passes to the old miser's servants, the Boffins. The Boffins are simple, kind-hearted old folks, of the type who populate many of Dickens' novels. Feeling an obligation to Bella Wilfer, they take her in and treat her as their daughter. Meanwhile, the Boffins' good fortune attracts other characters to them.
Silas Wegg is a one-legged peddler who has set up a stall near the mansion the Boffins move into. He is a seller of popular ballads, and the illiterate Mr. Boffin hires him to read to him, and later to house-sit the Boffins' old house, and to guard the three heaps of dust that Harmon Senior left behind. Wegg schemes to get a piece of the Boffin fortune, along with Mr. Venus, an "articulator of human bones." Wegg provides much of the novel's comic relief with his mangling of the ballads he sells. His incomprehensible version of Auld Lang Syne has to be read to be believed.
John Rokesmith is a young man who becomes Mr. Boffin's secretary. Dickens doesn't really try to conceal the fact that this is John Harmon, who for obscure reasons has engineered his own disappearance. He soon falls in love with Bella Wilfer, a spoiled and petulant girl who somewhat resembles Estella from Great Expectations, and who wants nothing to do with a mere secretary.
The second plot concerns Gaffer Hexam, a man whose occupation is fishing bodies out of the river. Not long after fishing the body of John Harmon out of the river, he is killed in mysterious circumstances, leaving his children, Lizzie and Charley, to fend for themselves. Charley is an ambitious boy in the mold of earlier Dickens heroes such as Pip and David Copperfield, but in this book, his ambition gets the best of him. Lizzie, his older sister, is beautiful and virtuous, but also devoted to her father, who is an unpleasant character. She attracts the attention of an indolent young lawyer of a higher class, Eugene Wrayburn, and also attracts Charley's psychopathic schoolmaster, Bradley Headstone.
The third plot concerns a social-climbing couple, the Veneerings, and the various characters who inhabit their circle-- the nobleman's poor relation Twemlow, Eugene Wrayburn and his friend Mortimer Lightwood, the overbearing Mr. Podsnap, the shrill Lady Tippins, and the Lammles, who married each believing that the other was rich. This plot hasn't aged all that well, being a satire of things that no one remembers.
One of the novel's most interesting characters is the schoolmaster, Headstone. He is a dark reflection of earlier characters like Pip, who passionately stalked Estella. There isn't much benign about Headstone, however, and when Lizzie rejects him, he snaps, and begins stalking Wrayburn, who he blames for his disappointment. Eventually Headstone will make an attempt on Wrayburn's life.
Dickens' interweaving of his themes and characters is masterful at times, though only the second plot, involving Lizzie Hexam and her suitors, is fully realized. The resolution of the John Rokesmith--Bella Wilfer plot is uncomfortably misogynistic, as it turns out that the Boffins and Rokesmith were in some kind of collusion to reform her character.
After "Our Mutual Friend", Dickens wrote only one more book, The Mystery of Edwin Drood, which was unfinished when he died in 1870, at the age of 58. Several of the character "types" carry over into that novel, most notably Bradley Headstone in an even darker, more villainous version as Jack Jasper.