When Voyager encounters a massive energy wave, the ship receives a download of indecipherable information. The crew track the energy wave's ion trail and finds a stranded vessel with a wounded alien on board. They beam the creature to sickbay but it springs through the forcefield around the surgical bay and attacks Torres, secreting paralysing fluids into her bloodstream, latching onto her and using her as a life preserver by co-opting her vital organs. Not knowing how to remove the creature without harming her, the Doctor and Kim access that part of the ship's database containing specialist exobiology research by Cardassian exobiologist Crell Moset, and they make the information interactive by rendering it as a hologram. When Seven tries to access the alien ship's databanks it causes the vessel to destabilise and explode. When Janeway cannot decipher the alien message, she retransmits the signal on all subspace bands, hoping more of the species will hear and respond. Meanwhile the Doctor and holo-Moset operate on Torres. While they work to remove the creature, Voyager is hailed by another alien vessel that locks them in a tractor beam, but Janeway senses they only want their fellow back and mean no harm. In surgery, the Doctor overrides Moset's decision to kill the alien and instead administers a neural shock that weakens its motor control without permanent damage. The creature withdraws from Torres, its metabolism is restored and it is beamed to the waiting ship. Having learned from Ensign Tabor of the real Moset's barbaric medical methods and having heard Torres say she prefers not to be treated by Moset, the Doctor ignores holo-Moset's plea for continued existence and deletes holo-Moset from Voyager's database.

At some point before this episode a Voyager away team visited Lav'oti V.

The Voyager crew take turns in groups to attend the Doctor's slideshow/photo-essay.

on the holodeck, one of the Doctor's slides of time spent on Lav'oti V

The Doctor has a picture of Torres with her foot caught in a plasma injector.

The Doctor's program is not large enough to hold the additional data comprising the exobiology research by famous/notorious Cardassian Dr Crell Moset. Therefore Kim merges the ship computer's extensive database on exobiology with an interactive holographic matrix to create a hologram of Moset. The Doctor deletes the hologram shortly after the operation on Torres is successful.

holo-Moset

The open lift between the lower and upper stories of main engineering is seen in use. It is also seen in use in several other episodes e.g. [#170 Renaissance Man].

Seven takes the lift to descend to the lower engineering level

Seven exits the lift

There is minor damage to the hull plating on Deck 15. When an alien ship arrives in response to Janeway retransmitting the injured alien's message on all subspace bands, the alien ship uses a tractor beam to drain power from Voyager.