It was a busy Thursday last night with all of the Big 4 networks offering all-original lineups. Showing how far the networks have gone from the old notion of summer as a place for reruns, there were 10 original series on ABC, CBS, Fox, NBC and the CW last night, including a whopping 8 original dramas.

Returning for a third season on a new night to a far more competitive field than when it first burst into the summer scene in 2013, CBS’ Under the Dome (1.3 in adults 18-49, 6.2 million viewers) was down -38% from its Season 2 debut on Monday last June. This would be a series low for the mystery drama in Live+same day. Under the Dome will likely close the gap somewhat in time-shifting viewing, which has been on the rise for summer dramas this year as ABC’s The Whispers and Fox’s Wayward Pines have both been posting big ratings gains. The two-hour season premiere of Under the Dome, which still ranked as the highest-rated drama last night, was preceded by the Thursday season opener of Big Brother (2.0, 6.4 million), which was steady with the fast nationals for the Wednesday season premiere and ranked as the top program of the night in 18-49. CBS easily won the night with in 18-49 (1.5) and total viewers (6.3 million)

Boom! Featured ImageThe second premiere last night was the series debut of Fox’s “bomb-defusing” game show Boom!, which didn’t quite live to its name in the ratings department, opening with a ho-hum 0.9 in adults 18-49, up a tenth from the soft start for the Are You Smarter Than a Fifth Grader? revival last month. Wayward Pines (1.2), continues to make a case for renewal, steady with last week and a close second to Under the Dome among all original drama series last night. It will be interesting to see which of the two supernatural dramas, both big DVR gainers, will come up on top in L+3 and L+7.

Rookie-BlueThe third Thursday debut was the return of ABC’s Canadian import Rookie Blue (0.6), which fell a steep -45% from its last season premiere last June. Facing original competition on CBS, ABC’s dramas Astronaut’s Wives Club and Mistresses declined by double-digits in Week 2. Astronaut’s Wives Club (0.8) was down -27% from last week’s debut. Mistresses (0.7) was down -22%.

NBC’s Aquarius (0.6), just renewed for a second season based on its digital performance, was off -14% (0.1) from last week but has a good chance of getting adjusted up a tenth in the finals. In its first airing after being cancelled by NBC, Hannibal (0.4) was down -20%, hitting a low. NBC started the night in a solid fashion with Dateline (1.3), which hit a Thursday season high in total viewers, 6.9 million, ranking as the most watched program of the night.  On the CW, Beauty and the Beast (0.2) was down -33% to tie a series low.