The NCIS: LA team must find who compromised a classified vaccine project from a bio tech company. Meanwhile, Deeks struggles with his emotions upon returning to the field.

After Operational Psychologist Nate Getz fails to check in with Hetty while working undercover on a mission linking organized crime to terrorism, the team learns he is working with an infamous crime leader,

When DOJ Agent Lance Hamilton's partner is killed, Sam dons his previous undercover persona of "Switch" to find the culprit. Also, Kensi, Deeks, Rountree and Kilbride work to catch an aerospace engineer who stole classified Navy schematics.