The supernatural series, which stars Phil Glenister and Richard Wilson, made an encouraging start last week with 5.75m (24.1%). The second episode, shown yesterday at 7.45pm, averaged 4.83m (20.4%).
The programme broadcast on ITV1 just before Demons, a Harry Hill's TV Burp clip show, had managed 6.56m (28.3%). Before that, You've Been Framed had brought in 6.4m (28.7%).
BBC One's new gameshow Total Wipeout also took a tumble after an impressive debut last Saturday. The programme lost more than 1.5 million viewers in a slightly earlier timeslot, averaging 4.71m (22.6%) from 5.45pm.
At 6.45pm, Eurovision talent search Your Country Needs You continued with a decent 5.04m (22.2%).
The most-watched programme of the day was Lottery gameshow In It To Win It, which pulled in 6.86m (28.9%) for BBC One from 7.45pm. A subsequent visit to Casualty had 6.75m (28.5%).
After Demons, a new episode of All Star Family Fortunes kept 4.05m (17.2%) with ITV1, then a screening of The World Is Not Enough, with Pierce Brosnan as Bond, managed 2.68m (12.8%).
A History Of Scotland brought in 1.87m (7.9%) to BBC Two at 8.30pm, then an hour later, a rerun of Three Men In More Than One Boat interested 1.49m (6.9%).
The latest update from Celebrity Big Brother averaged 2.19m (9.6%) for Channel 4 in the 9pm hour, with an additional 185k (1%) watching on Channel 4+1. A screening of the horror movie Final Destination 3 followed with 1.55m (9.2%).
On Five, a rerun of NCIS had 1.11m (4.7%) at 8.25pm, then an hour later, the first in a new season of CSI: New York appealed to a sizable 2.76m (12.7%). A new season of Law & Order followed with 1.53m (8.8%).
BBC One remained number one in primetime with an average audience share of 24.5%, up three points on last week, while ITV1 slipped from 20.2% to 18.8%. BBC Two rose from 7.8% to 8%, while Five improved from 5.7% to 7.2% for fourth place. Channel 4 was last, dropping from 7.1% to 6.6%.
> Click here to read our review of Demons episode two
Ratings data supplied by Attentional