The series has its most-watched initial airing ever with a simulcast on BBC America and AMC.

Killing Eve made a killing in the ratings for its second-season premiere.

The BBC America thriller, which grew its audience with every episode last season (after three days of delayed viewing), continued that trend Sunday as its second-season premiere was simulcast on sister network AMC. The premiere hit series highs across the board, topping 1 million viewers for an initial telecast for the first time.

The episode averaged 1.17 million viewers across the two channels, a same-day series high by about half a million people. Its 439,000 adults 25-54 and 327,000 viewers in the adults 18-49 demographic were also series bests by a wide margin.

When AMC Networks head of entertainment networks Sarah Barnett (who previously ran BBC America) announced the simulcast plan for Killing Eve, she said the goal was to "introduce this fantastic storytelling to an even broader array of viewers and fans." It worked Sunday, exposing the drama starring Sandra Oh and Jodie Comer to a significantly larger niche.

The previous highs for the series in same-day ratings (airing only on BBC America) were 702,000 viewers, 270,000 adults 25-54 — both attained in the season one finale — and 176,000 adults 18-49 for the sixth episode. Sunday's airing put up gains of 67 percent in viewers, 63 percent in adults 25-54 and 86 percent in adults 18-49 over those previous bests. The season two premiere more than doubled Killing Eve's season one averages in all three measures.

Put another way, the 1.2 million viewers for the simulcast of Sunday's premiere — after one day — is almost equal to Killing Eve's previous three-day high of 1.25 million viewers. It's all but certain to record new series highs in live plus three-day ratings when they're released later in the week.

AMC, which is in about 10 million more homes than BBC America, drew about two-thirds of the premiere audience (769,000). BBC America hd 403,000 viewers.

AMC Networks picked up a third season of Killing Eve on Monday.

Nearly all of those viewers hung around for the on-air premiere of A Discovery of Witches. The British import, which previously aired on AMC Networks' streaming services Sundance Now and Shudder, drew 1.1 million viewers across both networks, and on AMC it actually built on Killing Eve, drawing 853,000 viewers. The BBC America telecast had about 250,000.

Follow THR.com/Ratings for more ratings news and numbers.

April 9, 7:50 a.m.: Updated with individual network numbers.