The question at the center of “Broadchurch,” a British crime drama starting Wednesday on BBC America, is who killed a boy found dead on a beach in the picturesque seaside town of the title. Less of a mystery is why it stars David Tennant as Detective Inspector Alec Hardy. Though relatively unknown in the States, this wiry, energetic Scottish actor has long stood out on Britain’s stages and screens. When he starred in the Royal Shakespeare Company’s 2008 production of “Hamlet,” the critic for The Guardian proclaimed, “David Tennant is the greatest Hamlet of his generation.” And, while he is one of 11 actors to have played the titular centuries-old Time Lord on the long-running science-fiction series “Doctor Who,” his portrayal was among the most popular.

Reached by phone in Glasgow, where he is filming a romantic comedy, “What We Did on Our Holiday,” Mr. Tennant, 42, spoke with Margy Rochlin about “Broadchurch,” which a review from The Mirror in London called the drama of the year, and his trick for measuring his growing American fan base. These are excerpts from the conversation.

Q. “Broadchurch” was a big hit when it was shown in England in March. What does it offer that other series don’t?

A. Very often in television crime dramas, for very obvious and often quite legitimate reasons, you don’t really feel the genuine impact of what crime does to the victim and those around it. In “Broadchurch,” you can taste the grief and the horror and the extraordinariness of this random ghastly event happening to these people. It just felt electrifyingly real. And [Alec Hardy] is a great character — he’s noble, inscrutable and rather taciturn.