Having completed his six-book series about a British spy in Berlin during World War II, David Downing has begun a series about a British spy during World War I. In “Jack of Spies,” his new hero, Jack McColl, is hopscotching around the world in 1913 as Europe stumbles ever closer to disaster. In the process, he manages to fall in love, to defy death as he foils several German plots, and to wonder sometimes whether the cloak-and-dagger life is really for him.

McColl, who’s 32, operates behind the cover of his job as a salesman for a British dealer of Maia luxury cars. Henry Ford’s Model T is the world’s most popular automobile, but there are rich men all around the globe who can’t resist a stylish, bottle green Maia. We first see McColl in a port city in China, where besides selling cars he’s spying on German naval operations. (“These ships were the reason for his brief visit, these ships and what they might do if war broke out.”) McColl isn’t an official spy; most upper-crust Brits at that point considered spying unseemly business for a gentleman. But one realist at the Admiralty has hired him as a freelancer who submits coded reports and sometimes has his expenses paid.

In 1913, everyone feared war was coming, but few could quite believe it. McColl meets a German who says scornfully of his country’s Kaiser, “He grew up playing soldiers, and he can’t seem to stop.”

McColl himself reflects that he had been “born into a world without automobiles or flying machines, phonographs or telephones, the wireless or moving pictures. . . . Who in his right mind would exchange this thrilling new world for battlefields soaked in blood? It felt so medieval.” Much worse than medieval, actually, and only months away.

McColl’s life is complicated when he falls hard for a globe-trotting American journalist and feminist . Caitlin smokes in public, demands the vote for women and, most important for McColl, believes in frequent sex, but not with all that career-ending sentimentality that often accompanies it.

In a further complication, Caitlin is Irish American and her brother is allied with the Irish Republicans, who are expected to support Germany if war breaks out. McColl’s bosses want him to spy on his lover’s family. Torn between lust and patriotism, he vows that “he would not betray her if he could possibly avoid it.”

McColl’s spying takes him from China to San Francisco, Chicago, New York, Mexico (where German agents are trying to claim oil supplies needed by the Royal Navy) and finally to London and Dublin. People keep trying to kill him, but he soldiers on. McColl likes to see himself as “a player in a global game in which men from various nations tested their wits against one another.” But he’s troubled, too, because he’s sympathetic with the Irish and Indian activists who are conspiring to throw off British domination.

Events spin out of control after the heir to the Austro-Hungarian throne is assassinated in Sarajevo. McColl wonders: Why should Britain “involve itself in a Continental squabble over a murdered archduke?” Still, as war engulfs Europe, he knows that, for all his doubts, he must serve his country.

“Jack of Spies” moves along briskly and offers interesting facts about events now a century past. It’s always entertaining, sometimes a bit too much so, as McColl triumphs too easily in improbable adventures. It’s pleasant enough popular fiction — it’s fun to read a book in which people buzz about in Model Ts — but it won’t bear comparison with today’s best spy novels. Still, you might finish it wondering what comes next in the series.

Certainly, McColl will keep trying to win the elusive Caitlin, who will pop up often as a war correspondent, and he’ll agonize about his headstrong younger brother, who quickly enlisted in the British army. There’s a rather likable German spy with whom McColl has matched wits in various trouble spots; he’ll surely be back.

One hopes the spy business will become more serious now that armies are marching. Trench warfare lies ahead and poison gas and millions of senseless deaths. McColl is an appealing character, but a world at war must be a good deal more gritty, more heartbreaking, than what we’ve seen so far.

Anderson reviews mysteries and thrillers regularly for Book World.