In the upcoming 'NCIS: Los Angeles' Season 9 Episode 5 titled 'Mountebank,' Sam (LL COOL J) will go undercover as a day trader to investigate the murder of a well-off banker with ties to the Russian mafia. Sam and the team will be aided by Arkady Kolcheck (guest star Vyto Ruginis) who tells the team they are up against something dangerous.

The squad in danger?

The preview for the upcoming episode shows what happened before the banker's car came into contact with a speeding truck. Sam and Callen (Chris O'Donnell) were then present at the scene and believed that the collision was no accident. The suspects of the alleged murder will soon be interrogated by Deeks (Eric Christian Olsen) and Kensi (Daniela Ruah).

In the promo, the wealthy Arkady Kolcheck is seen wearing a paisley robe, and is surrounded by women warning the team of the dangers in dealing with the Russian mafia. Deeks is also shown flexing his muscles in an arm wrestling match against a mobster in a club, supposedly looking for information on the Russian mafia. However, he is expected to have a difficult time as Kolcheck iterated that people are coming after them and that they are in grave danger. Fans will have to wait to see if Deeks extracts information from the bar patrons without getting hurt.

Mosley fears for the team

Also shown in the preview for 'Mountebank,' Mosley (new cast member Nia Long) worries that the team is up against something big, and orders the team to back off from the investigation. Although Sam and Callen appear as though they agree with Mosley, they seem determined to carry on with the investigation.

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Meanwhile, the synopsis for 'Mountebank' also reveals that one of Callen's aliases has become a victim of a credit card theft. Mosley thinks that the robbery is tied to something bigger. Could it possibly be the work of the Russian mafia?

In the previous episode, Sam and Callen were able to stop the attempted assassination on weapons executive Mr. Bradford (Chris McGarry). It was later revealed that it was his co-partner's wife Sasha Livingston (Rebecca Wisocky) who ordered his assassination. Livingston apparently did not want her husband to invest in other lines of business which cost them money. Both Livingston and her husband were arrested, but her husband claimed to have no hand in the assassination attempt.

'NCIS: Los Angeles' season 9 airs on Sundays at 9/8 PM on CBS and CBS All Access.