'NCIS' Season 13 episode 21 spoilers: Gibbs reunites with his FBI counterpart to pursue British outlaws in ‘Return to Sender’

“NCIS” returns with a brand new episode on Tuesday, promising to deliver heart-stopping action in “Return to Sender.” Leroy Jethro Gibbs (Mark Harmon) collaborates with familiar faces from the FBI and Homeland Security to chase down two British escaped convicts. The outlaws, one of whom was identified as a spy, manage to cross international borders and set foot in the US.

Recurring guest stars Joe Spano and Alan Dale have both signed up to appear in the April 19 run to play as FBI Special Agent T.C. Fornell and Homeland Senior Division Chief Thomas Morrow, respectively. They join other “NCIS” cast members who will also be featured on the upcoming episode, including Anthony DiNozzo (Michael Weatherly), Timothy McGee (Sean Murray), Eleanor Bishop (Emily Wickersham) and Jimmy Palmer (Brian Dietzen). Also appearing on the “NCIS” Season 13 episode 21 are Leon Vance (Rocky Carroll), Abby Sciuto (Pauley Perrette) and Dr Donald Mallard (David McCallum).

Spoiler alert! This update contains more "NCIS” Season 13 spoilers. Read on at your own risk if you have not watched the latest episode.

TV Guide reports that on Tuesday’s episode, the “NCIS” team joins forces with the FBI and Homeland Security to delve into a case of two British men who escaped from prison, hauled themselves across continents, and arrived in the US via a shipping container. McGee, on the other hand, is out to find an apartment and is determined to know how DiNozzo could afford living in an extremely extravagant place.

“NCIS” also posted sneak peeks of its April 19 episode on its YouTube page . The first preview video shows how the NCIS tags team with the FBI on a case that unravels until the very end. Tension brews between Gibbs and Fornell as they are forced to collaborate to solve the case.

In another teaser, Gibbs and Fornell explore a laser tag arena which has become a crime scene after two bodies – the owner’s and the janitor’s – are found. They were murdered by the convicted fugitives, who also stole weapons and cash. Fornell could not help but wonder who the establishment owner was, and her relation to the British prisoners.

Spoiler TV reports that Alan Dale (Homeland Senior Division Chief Tom Morrow), Vince Nappo (Jacob Scott), Dan Hildebrand (Cassio Chavez), Kate Vernon (Caroline Morrow), Andy Beckwith (HM Prison Service Custodial Manager Chester Grimm), Douglas Olsson (Zaynak Darbenian),Tiffany Ariany (Katie Darbenian) and Jill Czarnowski (NCIS Tech) will also appear on “NCIS” Season 13 episode 21. “Return to Sender” is directed by Leslie Libman and written by Christopher J. Waild.

Find out what happens next on “NCIS” Season 13, which airs in the US on CBS every Tuesday, 8/7c.