"Scorpion" returns on CBS with an intense episode of season 2 at 9pm on Monday, 12 October. Episode 4, "Robots", will focus on Walter O'Brien (Elyes Gabel) and team's new mission that will put everyone in danger.

The official synopsis of the upcoming sequel read: "Walter, Cabe and Happy are trapped with the crew in a top secret submarine when an explosion sends it to the bottom of the ocean with limited oxygen and a self-destruct function that will soon activate."

While focusing on the team's new mission, the episode might also feature the relationship updates of each of the members. CLICK HERE to watch the fourth episode of season 2 live online on CBS at 9pm on Monday, 12 October.

The season, which began with an introduction of a bonding between Walter and Paige Dineen (Katharine McPhee), gradually addressed the romance between Sylvester Dodd (Ari Stidham) and Megan O'Brien (Camille Guaty) by the third episode.

So now its Tobias M Curtis aka Toby (Eddie Kaye Thomas) and Happy Quinn's (Jadyn Wong) turn to get back together. However, the previous episode indicated that the mechanical engineer wants to move on with her new friend. So fans of the television series can tune in to CBS at 9pm on Monday, 12 October, to catch up with Walter and his team.

Other cast members to appear in "Scorpion" season 2 episode 4 include Kevin Weisman as Ray, Lamar Stewart as Officer Chris Johnson, Jamie McShane as Patrick Quinn, Liz Jenkins as Lot Attendant, Pete Giovine as Chet, Travis Van Winkle as Ensign Nathan Hall and Jeff Corbett as Captain Steven Jones.

Watch the trailer of "Robots" below: