In Plain Sight (2008)

S3E4 Whistle Stop

Mary and Marshall team up with FBI Agent Mike Faber to persuade his informant to join the Witness Protection Program. However, despite their persistence, the informant declines their offer and finds himself in serious danger. After a tense rescue, where Mary, Marshall, and Agent Faber save him from imminent peril, the informant ultimately decides to accept their help, and he and his family agree to enter WITSEC.