Lovers’ Vows, by Mrs. Inchbald, is a translation and adaptation of a German play by Kotzebue, Natural Son (or Child of Love ).
Mrs. Inchbald protests in her preface that she had to change the speeches of Amelia (the part played by Mary Crawford) because they were far too bold for an English audience. Even so, Amelia is amazingly forthright about her love, as also Agatha (Maria Bertram) about her seduction and illegitimate son, and one can see why this play was thought by Edmund and Fanny to be highly improper for the young ladies in the Mansfield Park group, and why Edmund, rehearsing the Anhalt-Amelia scenes together with Mary Crawford, is drawn more and more into love for Mary. One may also note the rather scandalous willingness of these young people to hold Mr. Rushworth (playing Count Cassel) up to the mirror with such lines as this:
Baron: But if it happens that birth and fortune are joined with sense and virtue --
Mary Crawford, in the novel, also comments on Mr. Rushworth’s becoming a bit jealous at the "mother and son" embraces of Maria as Agatha and Henry Crawford as Frederick.
Agatha (Maria Bertram) is discovered, poor, ill and starving, pleading with the churlish Landlord of an inn for charity. Her son Frederick, (Henry Crawford) long away at the wars, arrives on leave and finds her in this condition. He is able to place her with a charitable Cottager (Tom Bertram) and his rather crabby Wife (Mrs. Grant), whose remarks are part of the comic relief, but she is on the brink of death due to her privations.
A crisis arises when Frederick tells his mother that he has returned in search of his official German birth certificate, and she tells him that he does not have one because he has no official father. Frederick had not known until this moment that he was a bastard. He is crushed, but refuses to judge his mother. He is now running out of money and desperate as to how to provide for her.
Meanwhile, up at the Castle, Baron von Wildenhaim (Mr. Yates) has returned from a long sojourn abroad, where his wife has recently died. He has one child, a daughter, Amelia (Mary Crawford), who has been instructed by a tutor, the clergyman, Mr. Anhalt (Edmund Bertram). Among his servants, the most prominent is an old Butler, named Verdun, (Tom Bertram) who serves as comic relief: he insists on turning the day’s events, or messages that he has to give, into ridiculous rhymes, and delivering them with an insistent sense of "stage presence."
Visiting with Baron von Wildenhaim is another nobleman, the foppish and empty-headed Count Cassel (Mr. Rushworth). He is interested in marrying Amelia, but the Baron is uneasy about the idea. He perceives that Amelia has no romantic interest in Cassel, and he asks Mr. Anhalt to probe her on her ideas about marriage and try to guide her properly. Amelia, however, has her own notions on the subject, and tries to get Mr. Anhalt to confess that he returns her love for him. Knowing the great class barrier between the two, Mr. Anhalt manfully tries to conceal that he does, in fact, love Amelia.
Frederick, desperate, attempts to rob the Baron when sufficient charity for his mother is refused. He is subdued and imprisoned, and is fast on the road to execution.
In the closing scenes, Frederick is discovered to be the Baron’s son and the repentant Baron pardons him, and rescues Agatha, whom he had deserted and cast off. He thinks that generous charity will be enough, but the upright Mr. Anhalt preaches to him that marriage is the only proper amends he can make to Agatha. In addition, the Baron is now so far convinced that marriages made under pressures of family pride are wicked, and love matches are to be approved, that he joins the hands of Mr. Anhalt and Amelia.