In a letter to Rayner Unwin in August 1953, Tolkien proposed the volume's title and considered leaving it vague, naming the ambiguous two as Orthanc and Barad-dûr, or Minas Tirith and Barad-dûr, or Orthanc and the Tower of Cirith Ungol. In another letter, in January 1954, he stated that he was "not at all happy about the title The Two Towers", writing that if the title had "any real reference in it to Vol II" it would have to "refer to Orthanc and the Tower of Cirith Ungol (his italics). He at once added that this would however be "very misleading", since there was "so much made of the basic opposition of the Dark Tower and Minas Tirith". However, a month later, he wrote a note that is included at the end of The Fellowship of the Ring, and later drew a cover illustration, both of which identified the pair as Minas Morgul and Orthanc. In the illustration, Minas Morgul is a white tower, with a thin waning moon above it, in reference to its original name, Minas Ithil, the Tower of the Rising Moon. Orthanc is shown as a black tower, three-horned, with Saruman's sign of the White Hand beside it. A Nazgûl flies between the two towers.

The narrative in the volume is interlaced, unlike the largely linear narrative in The Fellowship of the Ring, as the Fellowship is broken and the different groups pursue their own quests. The main quest, to destroy the One Ring, does not progress at all in book 3; conversely, the other quests do not make progress in book 4 as Frodo and Sam continue their dangerous journey towards Mordor. The timeline is more complex than this would suggest, as many smaller-scale interlacings occur as the characters travel through Middle-earth.

Interlacing allowed Tolkien to weave an elaborately intricate story, presented through the eyes of the Hobbit protagonists, "underscoring [their] frequent bewilderment and disorientation". Most directly, this is achieved by letting the reader know only what one character sees as he struggles forwards, not knowing what lies ahead, where his friends are, or whether the quest has already failed. The bewilderment of the reader is minimized by the use of synchronizing 'narrative landmarks', such as the brooch dropped by Pippin and discovered by Aragorn. Equally, interlacing enables Tolkien to create suspense and "cliffhanger" section endings, as when the Ents and Huorns appear suddenly and decisively in the eucatastrophe on the battlefield of Helm's Deep.

The Tolkien scholar Richard C. West writes that every reader must notice to some degree "the apparently meandering manner of the plot", where things happen apparently casually, as if by chance, as in real life. West illustrates this by examining Merry and Pippin's meeting with the Ents. This causes the Ents to overthrow their enemy Saruman, who was also the enemy of the kingdom of Rohan. This frees up Rohan to go to the aid of Gondor in their war with Sauron. The two Hobbits would never have met the Ents unless Saruman's Orcs had captured them. The Hobbits would not have escaped the Orcs unless Éomer's band of Riders of Rohan, disobeying orders from the King, had hunted the Orc intruders down. West states that each group and character has their own motivation, but their stories interact. It feels natural, and may appear "loose", but "everything is interconnected." The interlacing allows Tolkien to make hidden connections that can only be grasped retrospectively, as the reader realizes on reflection that certain events happened at the same time. Interlace, West notes, can "show purpose or pattern behind change". This can appear, Shippey writes, as luck, where in daily life it is uncertain whether this is "something completely humdrum and practical or something mysterious and supernatural".

Donald Barr in The New York Times gave the book a positive review, calling it "an extraordinary work – pure excitement, unencumbered narrative, moral warmth, barefaced rejoicing in beauty, but excitement most of all".

Anthony Boucher, reviewing the volume in The Magazine of Fantasy & Science Fiction, wrote that The Two Towers "makes inordinate demands upon the patience of its readers" with passages which "could be lopped away without affecting form or content". Nevertheless, he lavished praise on the volume, saying "no writer save E. R. Eddison has ever so satisfactorily and compellingly created his own mythology and made it come vividly alive ... described in some of the most sheerly beautiful prose that this harsh decade has seen in print."

The Times Literary Supplement called it a "prose epic in praise of courage" and stated that Tolkien's Westernesse "comes to rank in the reader's imagination with Asgard and Camelot".

John Jordan, admiring the book's narrative in the Irish Press, wrote of its "weaving of epic, heroic romance, parable, and fairy tale, and the more adventurous kind of detective story, into a pattern at once strange and curiously familiar to our experience". He compared the wizard Gandalf's death and reappearance to Christ's resurrection, writing that this could be done "without irreverence" because of Tolkien's seriousness about good and evil.

Mahmud Manzalaoui, in the Egyptian Gazette, wrote that the book "has not pleased readers of the staple modern psychological novel", but that it signified a new trend in fiction.

In The Observer, the Scottish poet Edwin Muir, who had praised The Fellowship of the Ring, called Tolkien's invention of the Ents and his account of the Battle of Helm's Deep magnificent. He wrote that contrary to some people's assumption, one could not equate the Ring to the atomic bomb; rather, it directly represented evil.

• Carpenter, Humphrey, ed. (2023) [1981]. The Letters of J. R. R. Tolkien: Revised and Expanded Edition. New York: Harper Collins. ISBN 978-0-35-865298-4.
• Holmes, John R. (2014). "The Lord of the Rings". In Lee, Stuart D. (ed.). A Companion to J. R. R. Tolkien. Wiley-Blackwell. pp. 133–145. ISBN 978-0-4706-5982-3.
• Noel, Ruth S. (1974). The Languages of Tolkien's Middle-earth. Houghton Mifflin. p. 170. ISBN 0-395-29129-1.
• Shippey, Tom (2005) [1982]. The Road to Middle-Earth: How J. R. R. Tolkien Created a New Mythology (Third ed.). HarperCollins. ISBN 978-0-261-10275-0.
• Sturgis, Amy H. (2013) [2007]. "Lord of the Rings, The". In Drout, Michael D. C. (ed.). J.R.R. Tolkien Encyclopedia. Routledge. p. 389. ISBN 978-0-415-86511-1.
• Tolkien, J. R. R. (1954a). The Fellowship of the Ring. The Lord of the Rings. Boston: Houghton Mifflin. OCLC 9552942.
• Tolkien, J. R. R. (1954). The Two Towers. The Lord of the Rings. Boston: Houghton Mifflin. OCLC 1042159111.
• West, Richard C. (1975). "The Interlace Structure of The Lord of the Rings". In Jared Lobdell (ed.). A Tolkien Compass. Open Court. pp. 77–94. ISBN 978-0-87548-303-0.

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