In "Terra Incognita," the next episode of the fourth season of the CBS drama "Person of Interest," John Reese (Jim Caviezel) decides to take on an old case from slain Detective Joss Carter (previously played by Taraji P. Henson) after his grief inspires him to honor her memory.

But he may also find that his new mission may lead him on a dangerous path with potentially fatal consequences, according to Hollywood Hills. 

In the previous episode, as International Business Times points out, Reese was able to successfully protect the CEO of a software company. But that led him directly back to his grief for Carter, who was killed last season by Officer Patrick Simmons (Robert John Burke). Carter had saved Carl Elias (Enrico Colantoni) before she was murdered, so in honor of her sacrifice, he ordered Anthony Marconi (David Valcin) to take out Simmons.

Carter was assigned a homicide case before her death, but she was never able to work it through to completion. The complex danger of the case, however, will lead Reese to a potentially perilous conclusion. But Reese will follow it through to completion at the risk of his own life to honor her memory.

To date, all four seasons of "Person of Interest" have been met with critical acclaim. Metacritic gave it a user score of 8.7 (based off 49 ratings) and review aggregator website Rotten Tomatoes gave it a whopping 100 percent rating with a 92 percent audience score. It is probably safe to say that most fans really love this show.

There are only three episodes left in this season on CBS, which include "Terra Incognita" on April 14, "Asylum" on April 28 and "YHWH" on May 5. There has been no word yet on what Season 5 will hold for us or what storylines might be returning for possible conclusions.