Before the Titanic sails out, Peter Pietkov aka Peter the Painter or Policemen killer has been wreaking havoc on the streets of London. When Winston Churchill inspects the bodies of two murdered policemen, killed by the gang of Peter Pietkov, Churchill delares he wants Pietkov found.
Meanwhile, in a basement, Peter Lubov seems to be hiding from the police patrolling the streets.
That night on board the Titanic, Lubov has a conversation with Mary's husband Jim Maloney. Lubov and Mary constantly exchange brief looks at each other, which Jim doesn't appear to notice. Mary suddenly drops her cork, which rolls to Peter. He brings it back to her, making her nervous. She reluctantly thanks him, without looking at him anymore. Jim noticed the weird behaviour of her wife.
Later, Lubov is reading a book, but another passenger keeps looking at him, smiling. Eventually, the passenger tries to make a conversation, but Lubov avoids him. The passenger moves to Lubov's table and introduces himself as David Evans, a retired army man. When Evans says Lubov looks familiar to him, Lubov angrily says he is not.
That Sunday, Lubov attends a church meeting in steerage with the entire Maloney family. Lubov then says to Jim he is going to get another "dose of religion", an Anglican church meeting in first class. Jim is a bit surprised by this, he never expected Lubov to be a churchgoer. Mary decides to go there as well, to get a look at First Class. Jim had already seen First Class (because he wired the ship) and takes the children back to his cabin.
When Lubov arrives in First Class, he sees Mary Maloney is already there and he takes a seat next to her. When he tells her not to be afraid of her feelings, she moves to another seat.
When the ship is sinking, steward Turnbull refuses to allow the Maloney family to go to the lifeboats. Lubov grabs Turnbull and Mary rushes through the gate with her four children, but two other stewards close and lock the gate again, trapping Lubov in steerage with Jim Maloney.
When Lubov goes for a walk on deck, he finds Mary Maloney again. She finally confesses to him and he drags her into a kiss. Suddenly Mary's husband Jim intterupts them and starts to beat up Lubov. Mary holds him back and Lubov just walks off.
When the ship is sinking, Lubov stands in a corner while stewards keep them down in steerage. Finally, steward Hart takes a group of women and children through the gate, but steward Turnbull quickly cuts off the line. Jim Maloney wants to get his wife and children through, but Turnbull is getting bossy. When Lubov intermingles, he grabs Turnbull and Mary escapes with her children. Another steward frees Turnbull before Lubov can kill him, and closes the gate, leaving Jim Maloney and Lubov still trapped down below. Witnessing this, David Evans then lures Lubov far away from eye witnesses by saying he found another way up. But Evans now had remembered why Lubov seemes familliar. He shoves Lubov to the wall and identifies him as Peter Pietkov, Peter the Painter, Peter the Policeman killer. Lubov snaps Evans' neck and returns to the gate.
Fireman Mario Sandrini appears on the other side of the gate and points to the women and children still trapped down. Lubov offers Jim Maloney to go up together and se the rest of the Maloney family in a lifeboat, then they can fight their issue about Mary. Turnbull opens the gate and Lubov escapes with Jim. 
He follows Jim to A Deck, where lifeboat 15 is being loaded. Mary and the kids try to board the lifeboat, but she's trampled. A stranger tries to assist her, only to be stopped by a jealous Jim. Mary calms his husband down and they all approach Murdoch to the boat. Hugh manages to override Murdoch's command to stop loading the boat and Mary enters with the children. Murdoch orders steward Hart to get in the boat and take charge.
Suddenly, Theresa panicks and bolts back on the Titanic. Jim abandons Mary to go find her. Lubov realizes he has to help him and will not survive himself. He goes to the lifeboat, says "remember me" to Mary and goes to look for Theresa.
He stumbles into Jim very soon. Lubov manages to put the issue about Mary aside and suggests to split up to look for Theresa.
Lubov soon wanders through a flooding corridor, shouting Theresa's name. Paolo Sandrini hears it and summons Lubov to help him free his trapped brother and the Gatti's waiters. Lubov, with his locksmith skills, manages to open the door of the cupboard just in time for Mario to escape and survive. Lubov stays behind in the flooding corridor, having done his final good deed by helping Mario survive the sinking.
Eventually Theresa will be found, only to die together with her father.