The show, co-created by Life On Mars writers Matthew Graham and Ashley Pharoah, stars Julie Graham and Adrian Lester as academics whose discoveries lead them into the mysterious and bizarre.
Last night's opener failed to impress critics but was watched by 6.8m (30.5%) and easily led its 9pm to 10pm slot. The show was also the most watched programme of the day on any channel, even ahead of the 6m (31.1%) audience for EastEnders.
Gordon Ramsay's F Word attracted another strong audience, meanwhile, putting Channel 4 in second place for the 9pm hour with 3.7m (16.4%). At 10pm Big Brother brought in another decent crowd of 3.4m (19.7%).
ITV1 drama repeat Doc Martin could only attract 3.3m (14.9%) in the 9pm hour while Five drew 1.2m (5.3%) for a CSI: Crime Scene Investigation repeat.
On BBC Two, a repeat of Richard Hammond Meets Evel Knievel, which was filmed shortly before the motorcycle stuntman's death, drew 1m (4.4%).