To solve the case of how “The Mysteries of Laura,” NBC’s police procedural starring Debra Messing as mom/homicide detective, was the top-rated new drama of the night, look no further than its lead-in. The two-hour finale of “America’s Got Talent” easily won the night with a 2.4/8 rating in the 18-49 demo, with “Laura” retaining 80% of that audience to bring in 2.0/7 in 18-49, 10.2 million viewers overall.

This also makes “Laura” — which went up against the finale of “Extant” on CBS and a rerun of “Nashville” on ABC in the 10 p.m. timeslot — the most-watched debut on any network since the “Believe” preview out of “The Voice” last spring. That’s a stark contrast to NBC’s debut in that time period last year: The remake of “Ironside,” which brought in 1.3 in 18-49 with 6.8 million viewers overall. It remains to be seen if “Laura” will hold onto these numbers when it moves to its regular 8 p.m. timeslot next week.

“Talent” also scored its highest ratings since its season debut in July, although CBS’ “Big Brother” was first in A18-49 in the 8 p.m. hour.

Fox’s “Red Band Society” also debuted on Wednesday with a 1.3/4 rating, albeit with the challenge of competing against the “Talent” finale in the 9 p.m. timeslot, and held steady in the second half-hour in all categories. (Fox aired “X Factor” in this time period last year, which brought in 4.1/7 overall and 2.3/7 in A18-49). The pilot of “Red Band Society,” a series with a strong teen focus, was also released in August on YouTube.

ABC spent the night in reruns, with solid numbers for “The Goldbergs,” “The Middle” and “Modern Family.” The CW lost the night with a new episode of “Penn & Teller: Fool Us” and a rerun of “The 100.”