John Marchmont's Legacy begins with Edward Arundel, destined for the army, bumping into his old teacher, the title character, working on a London stage. There is a hope that Marchmont will come into property but, until then, he and his young daughter, Mary, are living in poverty. Thanks to Edward's kindness, John Marchmont trusts him with the welfare of his daughter if they come into the inheritance and he dies. John is particularly worried about the ambitions of his brother, Paul Marchmont. John does come into his property and decides to marry Edward's cousin, Olivia, to provide a good mother figure for Mary. What he doesn't know is that Olivia has been in love with Edward for years and only marries him because Edward doesn't want her. After John's death, however, the household changes and when Edward falls in love with Mary, it's something Olivia struggles to accept. And then Paul Marchmont arrives...
By far, the most interesting character in this novel is Olivia. Her love for Edward pervades the novel, even though she accepts it's a damaging love, and the jealousy which emerges from it is inevitable but still fascinating to read. In comparison, the nice Mary feels somewhat like a cardboard cut out. Her courtship with Edward is very sentimental and childish in tone. Mary doesn't seem to grow up out of the child Edward first encounters and is subsequently made something of an angel. Of course, this works as an excellent contrast to Olivia but it also serves to highlight that Olivia is one of Braddon's best creations while Mary languishes amongst the stereotypical insipid 'good' heroines of sensation fiction.
The plot suffers from an abundance of coincidental incidents, as many sensation novels do. Being a seasoned reader of the form, I'd pretty much ascertained what was going to happen a few chapters in with John's prophetic mistrust of his brother and Olivia's pervading love for Edward. It did mean that I spent a good proportion of the second half of the novel frustrated and waiting for the inevitable revelation.
I also detected a problem which it seems Braddon struggled with - the introduction of another 'good' heroine, Belinda, which essentially creates a surplus going into the final pages. I'll allow you to discover for yourself how this is resolved.
Ultimately, John Marchmont's Legacy is a good novel mainly because of Olivia Marchmont. Of all the characters within these pages, she's the one that lingers.