04/03/2013 12:05 pm ET Updated Apr 04, 2013

David Tennant On 'Doctor Who' And The Very Different 'Spies Of Warsaw'

David Tennant has traveled far from the TARDIS.

In the two-part miniseries "Spies of Warsaw" (9 p.m. ET Wednesday, BBC America), Tennant has left behind his "Doctor Who" trench coat and traveled back in time to don the colorful uniform of a French army officer circa 1937.

In "Spies," Tennant plays Col. Jean-Francois Mercier, a French intelligence officer in Warsaw who meets Anna Skarbek, a League of Nations official played by Janet Montgomery ("Made in Jersey"). They are instantly attracted to each other, but Mercier's clandestine investigations dig up disturbing information about the Third Reich's preparations for war, and all of his relationships -- personal and professional -- become fraught with danger.

Mercier "is a career soldier. He was decorated for what he did in the First World War and for what he's done since, and he brings all that with him," said Tennant, who played the lead role on "Doctor Who" for three seasons. But in Mercier's work as a spy for France, "his morality comes up against his duty, because he's working for people who are looking to appease Hitler, and he comes to a point where he realizes he can't toe the party line any longer."

In that sense, Mercier shares a certain nobility with the Doctor, a character who, like the Frenchman, relies on his intelligence, savior faire and tenacity in any number of desperate situations. Of course, Mercier's demeanor is quite different from that of the energetic Time Lord, and it's a welcome change to see Tennant play a cagey, unsentimental character who's not afraid of a street fight.

The miniseries, which was shot in and around Warsaw, is based on a novel of the same name by Alan Furst, who often writes about characters who fall in love against a backdrop of subterfuge, espionage and war. Tennant said he hadn't heard of Furst when the project came to his attention, but he found the author's atmospheric novels invaluable when working on "Spies."

"As an actor who's handed the script, to have that as a source material -- it's so beautifully researched and the details ooze off the page," Tennant said. "You really get a sense of the period."

Indeed, part of what has gained Furst such a large and loyal following is the atmosphere of bittersweet romance that pervades his thoroughly researched books. His novels are full of flawed people who ultimately can't resist their deepest emotions, and events usually take place in Old World cities that stand on the cusp of catastrophe. Furst's reserved characters often have to take huge chances to save the lives of the people who matter to them, and in doing so, they demonstrate how difficult it is to be loyal and brave when the chips are down. The best part of these novels, which are suffused with romance and foreboding, is that Mercier (and other Furst characters like him) would hate to be described as heroes. They see themselves as survivors, at best.

For Tennant, part of the appeal of the "Spies" story (which also draws on "The Polish Officer," another Furst book) is that all that atmosphere and detail is put in service of recognizable stories that audiences can easily latch on to.

"It's set in this incredibly rich time in history, but what's really clever about ['Spies'] is that it's about people falling in love, and it's an adventure story, and that's what carries you through," he said. And paying tribute to the people of Warsaw was a side benefit.

"The Polish story is really under-told," he added.

For Mercier, danger does lurk around every corner, but for Tennant, it was an enjoyable change of pace to play a character who forthrightly enjoys all the trappings of the spy life: drinking, smoking, assignations on trains, etc.

"We all want to live in a world where we believe that smoking isn't bad for you," he said of traveling back in time to 1937.

Speaking of time travel, it was recently announced that Tennant will be returning to "Doctor Who" for the much-anticipated 50th anniversary special that will air this fall. He'll co-star with Rose Tyler (Billie Piper), John Hurt, Matt Smith's 11th Doctor and the new companion played by Jenna-Louise Coleman. Though I spoke to Tennnant months ago in Los Angeles, well before that deal was in place, he was very happy to reminisce about his time in the TARDIS.

"Just the making of the series was an incredibly happy time -- working with [former 'Doctor Who' executive producer Russell T Davies] and just being part of something that felt quite important at the time and is so celebrated," Tennant said. Still, the fact that the show is a cultural touchstone in the U.K., where its ratings are a big deal, meant that there was also "a huge pressure to that, which stops you from fully enjoying it as much when you're in it."

In America, however, he's recognized far less than he is in the U.K.: As he put it, "I don't have to wear a baseball cap everywhere here." And though every actor who enters the TARDIS wonders if the role will limit future career options, Tennant said that hadn't been the case for him.

"So far it's opened a great many more doors than it's closed, and I've managed to be busier than I could wish for, doing a wide variety of things," he said. "It's been a huge boon."

Critic Ryan McGee and I discuss "Spies of Warsaw," "Hannibal" and "Justified's" fourth season in this week's Talking TV podcast, which can be found here, on iTunes and below.