Underground set a record as WGN’s highest performing original series ever in its launch last night. The 10 PM airing drew 1.4M total viewers to rank No. 5 among all scripted series premieres on cable this broadcast TV season. The premiere’s 585K adults 25-54 ranks No. 7 in the TV season that started last September.

Across its four Wednesday night plays, the launch cumed 2.5M viewers, to stand as the best total-viewer opening ever for an original on WGN in same day viewing. The drama, created by Misha Green and Joe Pokaski, outpaced premieres of the network’s Outsiders by 27% and Salem by 6%. Across those four plays, Underground delivered 983K adults 25-54, surpassing Outsiders by 21%.

Picked up for a full 10-episode first season in February 2015, the TV project from Sony Pictures Television and Tribune Studios focuses on a group of slaves at a Georgia plantation who begin a 600 mile pre-Civil War trek to freedom via the Underground Railroad. It was the second highest trending topic on Twitter last night, behind only the Democratic debate on CNN and Univision, starring Bernie Sanders and Hillary Clinton.