The narrator of "Porphyria's Lover" is a man who has murdered his lover, Porphyria. He begins by describing the tumultuous weather of the night that has just passed. It has been rainy and windy, and the weather has put the speaker in a melancholy mood as he waits in his remote cabin for Porphyria to arrive.
Finally, she does, having left a society party and transcended her class expectations to visit him. Wet and cold, she tends to the fire and then leans against the narrator, professing quietly her love and assuring him she was not deterred by the storm.
He looks up into her face and realizes that she "worshipp'd" him in this moment, but that she would ultimately return to the embrace of social expectation. Taken by the purity of the moment, he does what comes naturally: he takes her hair and strangles her to death with it. He assures his listener that she died painlessly. After she dies, he unwinds her hair and lays her corpse out in a graceful pose with her eyes opened and her lifeless head on his shoulder.
As he speaks, they sit together in that position, and he is certain he has granted her greatest wish by allowing them to be together without any worries. He ends by remarking that God "has not yet said a word" against him.
"Porphyria's Lover," published in 1836, is one of Browning's first forays into the dramatic monologue form (though he wouldn't use that term for a while). The basic form of his dramatic monologues is a first person narrator who presents a highly subjective perspective on a story, with Browning's message coming out not through the text but through the ironic disconnect of what the speaker justifies and what is obvious to the audience.
In this poem, the irony is abundantly clear: the speaker has committed an atrocious act and yet justifies it as not only acceptable, but as noble. Throughout the poem, the imagery and ideas suggest an overarching conflict of order vs. chaos, with the most obvious manifestation being the way the speaker presents his beastly murder as an act of rationality and love.
The clearest example of the disconnect between order and chaos comes in the poetic form. The poetry follows an extremely regular meter of iambic tetrameter (four iambic feet per line), with a regular rhyme scheme. In other words, Browning, always a precise and meticulous poet, has made certain not to reflect madness or chaos in the rhyme scheme, but instead to mirror the speaker's belief that what he does is rational.
Indeed, the order that the speaker brings to such a chaotic act is explained with rather romantic rationale. Porphyria, it is implied, is a rich lady of high social standing, while the speaker, out in his remote cabin, is not. She has chosen on this night to leave the social order of the world and retreat into the chaos of the storm to quell her tumultuous feelings for this narrator. Thus there is some indication of the theme of class, though it is far less pervasive in the poem than are the large questions of human nature. When the speaker realizes that Porphyria ultimately will choose to return to the order of society, while simultaneously believing that she wishes to be with him – she "worshipp'd" him, after all – he chooses to immortalize this moment by removing her ability to leave.
In this line of thought lies the key to understanding much of Browning's poetry: his sense of subjective truth. Unlike most poets, whose messages, even when obtuse, are fully formed, Browning believes humans to be full of contradictions and malleable personalities that shift constantly, sometimes moment to moment. Even if we assume the speaker understands the situation correctly when he identifies Porphyria as purely devoted to him at the moment of the murder, we are also to believe that she will soon retreat to a different contradictory personality, one that prizes social acceptance. So what the speaker undertakes is in some ways a fallacious yet heroic goal: to save Porphyria from the tumultuous contradictions of human nature, to preserve her in a moment of pure happiness and contentment with existing in chaos.
It is also interesting how Browning uses so much stock, melodramatic imagery to set his poem up. While the storm certainly suits his ideas as a symbol of chaos (as opposed to the order of society), it is akin to the 'dark and stormy night' setups of traditional stories. However, once Porphyria enters, the poem moves to a more explicitly sexual place – notice the imagery as she undresses and dries herself – that suddenly equates those natural forces with the human forces of sexuality. The speaker, who had "listen'd with heart fit to break" to the storm, seems to recognize in both of these parallel forces the existence of the uncontrollable. Considering the Victorian period in which Browning wrote, this sense of sexual freedom could be expected to prompt a judgment from his audience on Porphyria as an unwed sexual woman, a judgment that is quickly reversed when she becomes the victim of an even darker human impulse than sexuality (though one most certainly tied in with it). It is worth mentioning that the speaker does not take any sexual license with her dead body, but instead tries to maintain a sense of the purity he had glimpsed in her, creating a tableaux with her head on his shoulder that evokes childish affection rather than adult depravity. As with all things, Browning complicates rather than simplifies.
The overarching message of the poem is thus that humans are full of contradictions. We are drawn to both the things we love and the things we hate, and we are eminently capable of rationalizing either choice. Through such measured and considered language, we are invited to approve of the murder even as it disgusts us, and in the murder itself we are to forgive the woman for what we (at least if we were Victorian) might have otherwise judged her. Humans are creatures of transience and chaos, even as we belabor the attempt to convince ourselves that we are rational and that our choices are sound.