"I was unprepared, really, for quite how many people watched it. And so I ended up not being able to get on the bus for fear of people going, 'Who did it?' " she said, laughing, afraid that "if they look in my eyes, they'll know" who the killer was.
"So I ended up spending a fortune on taxis for the last two weeks it was running."
In "Broadchurch," Colman plays Ellie Miller, a police detective in a small seaside town who finds herself working for an outsider, Alec Hardy (David Tennant, "Doctor Who"), after he gets the job she'd been expecting.
But, when the 11-year-old boy who'd been her son's closest friend is found murdered on a beach, "I think she becomes grateful that he's there," Colman said.
"She's kind, and she does [her job] for all the right reasons, to protect her community. But when it comes to this particular case, she is underqualified."
With two sons of her own, aged 7 and 5, Colman is as queasy as anyone about television's fixation on missing and murdered children.
"It's kind of an obsession, because it's such a horrific idea," she said. "It's slightly macabre, and I'm always disappointed in us all for wanting to watch it, but I think you can't help wanting to. . . . When something breaks on the news, some child is missing, I find myself looking everywhere, as if I have to find them."
The cast, Colman said, didn't know the identity of the killer until the script for the season's eighth and final episode arrived.
"It was an opportunity to play a lead, and it was so beautifully written, that first episode, that I trusted it was going" to be good, she said.
It also made her protective of Tennant, who's a much bigger star in Britain.
"I think he's amazing, how he handles it all," Colman said of her co-star. "He's eternally charming and patient.
"I just kind of wanted to protect him and to tell everyone to bugger off . . . . The weirdest thing is people holding their phones this far away from your face," she said, demonstrating with one hand. "As if affording you no more respect than a pigeon. . . . This is a horrible exchange. I can see that you're there. This is rude, it's rude."
"Oh, yeah. Not even looking at his face. Not speaking. People seem completely desensitized."
As for her own brush with fame, it's mostly passed, she said.
"They realize you're quite boring. And they stop."
(If you missed the premiere of "Broadchurch," it's available for streaming at bbcamerica.com.)
'Husbands' on the move
"Husbands," the classically funny, web-based "marriage equality" sitcom from Brad Bell and Jane Espenson ("Buffy the Vampire Slayer," "Once Upon a Time"), launches its third season Thursday at a new address: cwseed.com, where it will be joined on the CW's new digital outpost by three other web series, "Backpackers" and "P.E.T. Squad," and the animated "Gallery Mallory."
Amy Acker ("Much Ado About Nothing") and Philadelphia's Seth Green ("Robot Chicken") are among the guest stars in the first two episodes as "Husbands" Cheeks (Bell) and Brady (Sean Hemeon) attempt a dignified do-over, three months after their drunken wedding in Vegas.
You don't really need to know anything to join "Husbands" in progress, but if you want to see more, the first two seasons - they're short and pretty sweet - are on YouTube, linked from HusbandstheSeries.com.
On Twitter: @elgray