Voyager detects the signs of a wormhole and a course is set to investigate, in the hopes that it may shorten Voyager's journey to Earth. To the crew's disappointment, it is discovered to be a decaying micro-wormhole whose aperture is only about 30 centimetres (12 in) in diameter. Nevertheless, Captain Janeway suspects that it could be used to transmit a message to the Alpha Quadrant, and a micro-probe is launched into the wormhole to determine where it exits.
However, the probe gets stuck in gravitational eddies, and is unable to pass any further. Meanwhile, a vessel at the other end of the wormhole is investigating and making scans of the probe. The crew of Voyager detect the scans and make contact, using the probe as a communications relay. The vessel identifies itself as a Romulan ship, and confirms that the wormhole does indeed exit in the Alpha Quadrant.
Janeway convinces the Romulan captain to take securely-transmitted messages from the crew which can be passed on to Starfleet and the family of Voyager's crew members.
Before long, however, Chief Engineer Torres suggests to Janeway that the probe could be used as a relay not only for communications, but for transporting the crew directly back to the Alpha Quadrant. Several tests are conducted and all found successful. The Romulan captain arranges for a support vessel to rendezvous and accommodate the Voyager crew, and is then invited and transported to Voyager.
It is then discovered, however, that the Romulan (later to introduce himself as Dr. Telek R'Mor of the Romulan Astrophysical Academy) has been transported into the future by 20 years. The micro-wormhole not only exits in the Alpha Quadrant but also in the past. The crew are unable to transport back to the Alpha Quadrant for fear of altering history, and it is also decided that the Romulan should not try to prevent Voyager's fate before it occurs. Instead, an arrangement is made so that the Romulan delivers the messages in 20 years time, after Voyager has left the Alpha Quadrant.
After the Romulan is sent back to his ship and all contact ceased, Chief of Security Tuvok reveals that, upon researching the computer's data banks, the Romulan died four years before he could pass on the messages. Although it is suggested that someone else could have done it after his death, later episodes ("Message in a Bottle") establish that Starfleet instead learns about their fate four years later through the Doctor.