Vigil teases tense confrontation for the BBC drama in pictures for episode 4

Among the staffers on the vessel are Chief Petty Officer Elliot Glover (Evans), who can be seen arguing with Silva in an advance image from tonight's episode (see above).

Fans will be hoping for more secrets to be revealed as they attempt to unravel the conspiracy at the heart of the show, which the Vigil synopsis has teased will threaten Britain's national security.

Vigil has been a hit for BBC One thus far, earning glowing praise from critics and generating a lot of conversation across social media, particularly after episode one's shock twist.

It was thought that Line of Duty star Martin Compston would have a major role in the series, but in actual fact, he was killed off in a scene from the first instalment that left viewers reeling.

If you're counting down the minutes until tonight's episode, check out our biggest questions from Vigil episode three, which delivered some major revelations about the case and sparked more fan theories.

Another image from Vigil episode four gives us a glimpse at different scene with Glover. Check it out below.

Unlike many recent BBC productions, Vigil has not been launched as a box set on iPlayer as the broadcaster hopes viewers will watch along week-by-week rather than binge ahead as answers are slowly revealed.

Vigil continues tonight on BBC One at 9pm. Check out more of our Drama coverage or visit our TV Guide to see what's on tonight.