The three-part series, in which Nesbitt plays a maverick journalist who cannot go out in daylight and becomes caught up in a murderous government conspiracy, was watched by an 18% share of the audience to win the 9pm-10pm slot.
The second episode of BBC One's new comedy drama 'The Invisibles' sunk to 3.2m viewers and a 15.3% share, compared to 4.7m viewers last week.
The programme, in which Warren Clarke and Anthony Head play a pair of loveable rogues, was the second most watched show in the 9pm-10pm slot.
BBC Two's US import 'Heroes' pulled in 2.7m viewers and a 12.5% share between 9 and 10pm, for the third episode of an 11-part series.
Five's US medical drama 'House' held steady from last week, with 1.8m viewers and an 8.2% share in the same slot.
Channel 4's 'Grand Designs Live' netted 1.9m viewers and an 8.8% share between 9 and 10pm for the penultimate instalment of a six-part special. Including Channel 4+1's time-shifted audience, it drew 2m viewers and a 9.3% share.
Earlier in the evening, the cookery-based reality show 'Come Dine with Me' enticed 2.1m viewers and a 10.6% share between 8pm and 9pm. Including Channel 4+1, it had 2.3m viewers and an 11.8% share.