Compared to other thriller writers of the time, such as Ian Fleming, MacLean's books are exceptional in one way at least: they have an absence of sex and most are short on romance because MacLean thought that such diversions merely serve to slow down the action. Nor do the MacLean books resemble the more recent techno-thriller approach. Instead, he lets little hinder the flow of events in his books, making his heroes fight against seemingly unbeatable odds and often pushing them to the limits of their physical and mental endurance. MacLean's heroes are usually calm, cynical men entirely devoted to their work and often carrying some kind of secret knowledge. A characteristic twist is that one of the hero's closest companions turns out a traitor.
Nature, especially the sea and the Arctic north, plays an important part in MacLean's stories, and he used a variety of exotic parts of the world as settings to his books. Only one of them,
When Eight Bells Toll, is set in his native Scotland. MacLean's best books are often those in which he was able to make use of his own direct knowledge of warfare and seafare, such as
HMS Ulysses which is now considered a classic of naval fiction.
Stylistically, MacLean's novels can be broken down into four periods:
- HMS Ulysses through to The Last Frontier. These featured third-person narratives and a somewhat epic tone, and were mostly set during World War II. The Last Frontier contained overt philosophical and moral themes that were not well received. MacLean then switched gears to —
- Night Without End through to Ice Station Zebra. These all featured first person (and sometimes unreliable) narration laced with a dry, sardonic, self-deprecating humour, and were all set in contemporary times. These are MacLean's most intensely plotted tales, masterfully blending thriller and detective elements. MacLean then retired from writing for three years, returning with —
- When Eight Bells Toll through to Bear Island, a varied collection that still maintained a generally high quality, with some books harking back to each of the first two periods but usually taking a more cinematic approach (not surprising since he began writing screenplays during this time).
- The Way to Dusty Death to the end. There were no more first-person stories, and his prose is thought to have often sagged, with excessive dialogue, lazily described scenes, and under-developed characters. All the books sold reasonably well, but MacLean never regained his classic form.
Certain themes are repeated in virtually all of MacLean's novels. For example, they typically feature a male character who is depicted as physically and morally indestructible (for instance, Carrington in
HMS Ulysses; Andrea in
The Guns of Navarone); such characters are also often described as having an almost inhuman tolerance for alcohol consumption (for instance, the Count in
The Last Frontier; Jablonsky in
Fear is the Key). Other minor traits or actions also turn up in every book, such as the cliche of characters shaking their heads in order to come to their senses after receiving a blow to the head. "Mediterranean" or Latin American characters are almost always depicted as criminals (as with Gregori in
The Satan Bug, Miguel and Tony Carreras in
The Golden Rendezvous, and so forth).
Altogether, MacLean published 28 novels and a collection of short stories, as well as books about T. E. Lawrence and James Cook.
MacLean also wrote screenplays, some of them based on his novels and others later novelized by other writers. Around 1980, he was commissioned by an American movie production company to write a series of story outlines to be subsequently produced as movies. He invented the fictitious United Nations Anti-Crime Organization (UNACO), and the books were later completed by others. Among these are
Hostage Tower by John Denis and
Death Train by Alastair MacNeill. Some of these works bear little resemblance to MacLean's style, especially in their use of gratuitous sex and violence.
Many of MacLean's novels were made into films, but none completely captured the level of detail and the intensity of his writing style as exemplified in classics such as
Fear is the Key; the two most artistically and commercially successful film adaptations were
The Guns of Navarone and
Where Eagles Dare.
After his death, the popularity of his work saw a decline, and, according to Amazon.com, as of 2006 none of his novels are in print in the U.S. However, most are currently still in print in paperback in the UK.