Here is the official description for NCIS: Los Angeles season 6 episode 21, "Beacon" - airing April 20th.
Season 6 Episode 21 "Beacon"
CALLEN AND SAM ARE SHOCKED WHEN AN APPARENT MURDER VICTIM APPEARS AND ASKS FOR THEIR HELP
Callen and Sam are shocked when an old acquaintance, who they thought was the recent victim of a murder, appears and asks for their help. As the team investigates, they uncover a possible breach of America's economic sanctions against Russia.
Chris O’Donnell (NCIS Special Agent G. Callen)
LL COOL J (NCIS Special Agent Sam Hanna)
Linda Hunt (Operations Manager Henrietta “Hetty” Lange)
Daniela Ruah (NCIS Special Agent Kensi Blye)
Eric Christian Olsen (LAPD Detective Marty Deeks)
Barrett Foa (Tech Operator Eric Beale)
Renée Felice Smith (NCIS Intelligence Analyst Nell Jones)
Miguel Ferrer (NCIS Assistant Director Owen Granger)
guest & recurring cast:
Vyto Ruginis (Arkady Kolcheck)
Elizabeth Bogush (Joelle Taylor)
Aisha Kabia (Coast Guard Lieutenant Joyce Kelly)
Dan Warner (Man with Hoodie/Brett Smith)
Matt Stasi (Patrick Berkeley)
Elena Evangelo (Elia Berkeley)