"The BlackList's" upcoming Episode 17, "The Longevity Initiative," will bring viewers a more solidified presence of Tom Keen.

CarterMatt notes that throughout the season Tom has popped in and out of the series, but this episode will mark Tom as a more permanent fixture in the season.

This episode will also answer the question of whether Reddington is trying to become immortal. For some time now, Reddington has shown great interest in a man named Julian Powell, who is doing experiments that will give someone the ability to live forever.

In Episode 17, fans will see what transpires between Reddington and the man and what happens if Reddington gets a hold of the experiment.

Liz, who is now a free woman, is working with Reddington to track down Powell who is conducting his experiments and testing them on disabled patients, says Christian Today.

However, Reddington is able to contact Powell first. And instead of stopping Powell's experiment, viewers see Powell getting into Reddington's car, and the two appear to be discussing.

Meanwhile, Tom, having just confessed to murder in Episode 16, is now trying to avoid his enemies in D.C.

As shown in Episode 16, Reddington was able to track down Tom so that he would confess to the murder charges that his wife, Liz, was up against. Tom finally confessed and somehow was able to walk out of the court as a free man. But now that he is off the hook, Tom has some new obstacles to face.

Tom must now attempt to get out of D.C. without confronting the many enemies he made over the years.

Episode 17 guest stars include Lance Henriksen, Josh Close, Ralph Brown and Kevin Weisman, according to On the Flix.

Episode 17 of "The Blacklist" airs Thursday, March 26, at 9 p.m. EST on NBC.