In the season finale of "Scorpion," the team and crew are forced to face its most stern test yet as members join forces to try and save Walter (Elyes Gabel) from sure destruction.

According to Spoilers Guide, with the members "torn apart and uncertain about their future as a team," they still find themselves needing to come together for the sake of Walter, who's vehicle perilously "teeters on the side of a cliff."

"Postcards From the Edge," the season finale, airs April 20.

At the end of Episode 21, the tension developing between team members was almost palpable as Walter finally found out about agent Cabe Gallo's (Robert Patrick) long-held Baghdad mission secret. In that episode, Paige (Katharine McPhee) became a ball of emotions as she learned that Ralph had once put his life in danger to help the crew.

All this happened as Walter appeared to get courage to finally tell Paige his true feelings for her. SpoilerTV reports that as Walter struggles for survival this week, his only wish is to see Paige, who initially is nowhere to be found. But before all the drama ends, there is "an admission, a kiss and many tears."

Guest stars for the episode include Riley B. Smith as Ralph, David Fabrizio as Merrick, Andy Buckley as Richard and Leigh Ann-Rose as Darla, Michael Wiseman as the fire chief and Eric Davis as Officer Kinkirk.

According to TV Guide, the 31-year-old McPhee is also a former "American Idol" runner-up. Her self-titled debut album was released in 2007 and she followed that up with the release of "Unbroken" in 2010. McPhee has also appeared on such TV shows as "CSI: New York" and in the 2008 film "The House Bunny."

Earlier this year, CBS execs announced "Scorpion" will be returning for a second season. Back then, the show was ranked as the third most-watched new series of the season, averaging just under 15 million viewers.