Partners in Crime wrapped up its first three-part adventure with 4.49m (22.9%) on BBC One, according to overnight figures for Sunday (August 9).
The figure was down around half a million on the number who tuned in to see episode two of the David Walliams series last week.
Elsewhere, Countryfile topped the night with 5.95m (34.3%) at 7pm, while Fake or Fortune? appealed to 4.55m (23.3%) at 8pm.
On BBC Two, Dragons' Den continued with 3.11m (15.9%) at 8pm, while Odyssey attracted 1.21m (6.1%) at 9pm.
ITV's Nature Nuts with Julian Clary added 200,000 viewers with 1.39m (8.1%) at 7pm (158k/0.8% on +1), before Midsomer Murders intrigued 2.14m (11.0%) between 8pm and 10pm (220k/1.3%).
Over on Channel 4, The Dambusters' Great Escape gathered 640k (3.7%) at 7pm (160k/0.8%), while Experimental interested 490k (2.5%) at 8pm (91k/0.5%). Life of Pi followed with 1.71m (10.5%) at 9pm (241k/2.2%).
Channel 5's Police Interceptors: Unleashed entertained 816k (4.2%) at 8pm (69k/0.3%), while Takers brought in 731k (4.3%) at 9pm.
Meanwhile, Sky1's The Last Ship thrilled 126k (0.7%) at 8pm.
