Henry is an art historian who returns to England from the United States upon inheriting his family estate, and Cato is a Roman Catholic priest who is losing his faith and has secretly fallen in love with a seventeen-year-old boy .

The two main characters, Henry Marshalson and Cato Forbes, were childhood friends who grew up as neighbours in the English countryside.

On his father's early death, Henry's elder brother Sandy inherited all the property, including the family home, Laxlinden Hall.

Cato is the son of an atheist university professor and the older brother of Colette, who has left college and returned to her father's home.

Cato is in the process of losing his faith, and has secretly fallen in love with a seventeen-year-old boy called Beautiful Joe, who claims to be a petty criminal and an aspiring gangster.

[3] Lorna Sage remarks in her review of the novel that this deployment of "multiple contrasts and operlaps of its two heroes' careers" is "a technique at which Miss Murdoch has become so carelessly expert that one soon loses sight of its crude binary origins".

According to Peter J. Conradi, Henry wants to renounce the world and live in the sun, while Cato, having lost his faith, is trying to return to the cave.

[6] : 279  Cato's sudden conversion is described in Platonic terms, as he feels "as if he had not only emerged from the cave, but was looking at the Sun and finding that it was easy to look at".

[7]: 47 Henry and Cato was Iris Murdoch's eighteenth novel, and several reviewers addressed possible objections arising from her prolific output and continuity of themes.

The Washington Post review approvingly compared her "essentially 19th-century way of writing and working" to that of Anthony Trollope, and called Henry and Cato "another star for her literary firmament".

[8] Lorna Sage remarked that Murdoch's large and regular output demonstrated her "gift for making the variety of possible plots and characters seem inexhaustible".

Joyce Carol Oates called Henry and Cato "Murdoch's finest novel to date, and surely one of the major achievements in fiction in recent years".

Because the characters and plot are convincing the ideas and themes are realistically "embodied in the narrative", which is not always the case in Murdoch's novels, according to Oates.

Writing in The Globe and Mail, Margaret Laurence acknowledged the "narrative skill" and "intelligence" displayed in Henry and Cato, but found the characters unrealistic and too often merely representatives of the author's views.

[6]: 279  His discussion of the novel takes doubleness to be the main theme, and more specifically "chiasmus", in that the stories of the two men increasingly intersect and mirror each other.

In her study of Murdoch's work, Hilda Spear includes Henry and Cato as the last of a group of four novels, beginning with The Black Prince, in a chapter called Metaphors for Life.

The chapter title points to the fact that each of the novels is written in a "consciously deliberate" narrative style, in which the reader is reminded that "a story is being told".

This narrative style does not prevent the reader from becoming absorbed in the plot, however, and Spear suggests that Henry and Cato is among Murdoch's most accessible novels.

Brendan Craddock, Cato's friend and fellow priest, is a seemingly minor character who represents "a clearly defined good figure".