1. Sniper's Nest (1)

7.8

. 6 January 2015. 60 min

Nikki and Jack strive to track down a sniper at large in London and stem a public crisis.

2. Sniper's Nest (2)

8

. 7 January 2015. 60 min

Nikki and Jack investigate links between the victims to close the net on the killer.

3. Falling Angels (1)

8

. 12 January 2015. 60 min

Nikki and Jack investigate a man killed by a train on the London underground.

4. Falling Angels (2)

8.2

. 13 January 2015. 60 min

Nikki helps high-flying DI Luke Nelson unearth painful childhood memories.

5. Protection (1)

8

. 19 January 2015. 60 min

A suspected paedophile is found murdered in a children's playground.

6. Protection (2)

8

. 20 January 2015. 60 min

Nikki, Jack and Thomas focus in on Lizzie's movements on the night of Barge's murder.

7. Squaring the Circle (1)

7.8

. 26 January 2015. 60 min

The nanny of a Russian oligarch is killed in a botched assassination attempt.

8. Squaring the Circle (2)

7.7

. 27 January 2015. 60 min

A young woman working for the Doshis is found dead in Maksim's apartment.

9. One of Our Own (1)

7.8

. 2 February 2015. 60 min

The Lyell team are under pressure to catch the killer of an admired Essex police officer.

10. One of Our Own (2)

7.8

. 3 February 2015. 60 min

When the body of local criminal Jason Simons is found, the course of the case is changed.