Preview pictures and trailer of “Star Trek: Discovery” Season 2, episode 5 have been released online. The plot will revolve around the crew of the ship trying to save Sylvia Tilly (Mary Wiseman). That mission will bring back a very familiar dead character.

Tilly is paying the price for the technology Paul Stamets (Anthony Rapp) helped create. The new technology has had devastating impact on an alien species in the mycelium network. Captain Christopher Pike (Anson Mount) will take the crew on a dangerous rescue mission in the next episode.

A preview video of the next episode posted on Star Trek shows how the mission to save Tilly, who is trapped in the mycelium network, will not only put the lives of the crew in danger, but the whole ship could also be destroyed if they are unsuccessful. On the positive side, the episode will bring back Dr. Hugh Culber (Wilson Cruz).

Culber died in the previous season, but he has been appearing from time to time in the form of a ghost. Stamets hinted at Culber’s return previously when he felt that his partner wasn’t really gone.

In the next episode of “Star Trek: Discovery” Season 2, Culber will be a shadow of the man he once was. With ripped clothes and a long beard, the character can be seen sitting alone in the preview picture.

Joining Michael Burnham (Sonequa Martin-Green) in the rescue mission will be Stamets. Will Stamets be reunited with Culber? According to the official synopsis of the next episode, Stamets will not be prepared for what he will see during the rescue mission.

In an interview posted on the official “Star Trek” Facebook page, Rapp talked about the developing friendship between Stamets and Tilly. The actor pointed out that the relationship has already developed to a large extent in the first few episodes of Season 2. He explained that Tilly has become his character’s “sounding board” and “safe space” while dealing with all the other things that have been happening in Stamet’s life.

Star Trek Paul Stamets will meet a dead character in "Star Trek: Discovery" Season 2, episode 5.

Another preview picture of the next episode posted on the "Star Trek" website teases the return of Emperor Georgiou (Michelle Yeoh). The character is emerging as the chief problem solver for not only the Discovery but the Federation as well.

As far as Tilly is concerned, she will interact with the alien species from the mycelium network. While Tilly feels that she has been kidnapped, the alien will seek her help to possibly save her species.

New episodes of “Star Trek: Discovery” Season 2 air every Thursday at 8:30 p.m. EST and can be streamed on CBS All Access.