'Luther' Sneak Peek: What Does Halliday Find in Dr. Lake's Office? (VIDEO)

Meredith Jacobs
Exclusive BBC America

If you want to snoop in someone's office without getting caught, make sure you have someone willing to make multiple phone calls to distract the secretary.

That's exactly what DS Halliday (Wunmi Mosaku) has going for her in TV Insider's exclusive sneak peek of Sunday's episode of Luther.

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It's the return of the tough guys! And the long wait was worth it to revisit two of TV's least gentle dramas.

She and Luther (Idris Elba) questioned Dr. Jeremy Lake (Enzo Cilenti) in Episode 2 about "the intense nature" of the relationship between his wife, Vivien (Hermione Norris), and her patient. And now, in Episode 3, Halliday sneaks into the doctor's office under the pretense of looking for glasses she left in there.

Though his secretary says he would've given them to her, Halliday insists. "I won't break anything," she says.

(Des Willie/BBCAmerica)

And that's a promise she'll obviously want to keep since she's snooping through his files. But will she have enough time to find what she's looking for? Watch the clip below to find out.

Can Luther protect the innocent and save the young woman who was kidnapped by the relentless serial killer? And can he keep Cornelius's (Patrick Malahide) revenge from consuming him?

Luther, Sundays, 8/7c, BBC America