Identity Crisis ( episode ) Something is luring a former away team back to the planet they once investigated five years ago - an away team that La Forge was a part of . Summary . Teaser . In the observation lounge , Jean - Luc Picard , William Riker , Geordi La Forge , and Susanna Leijten are viewing a sensor log from an investigation Leijten and La Forge were part of five years ago , while attached to the . They were investigating the disappearance of 49 colonists from the Tarchannen III outpost . The other members of the " Victory " away team , Brevelle , Mendez , and Hickman , have now deserted their posts without any warning . A Federation supply ship has spotted Hickman ' s stolen shuttle and it is heading back to Tarchannen III . Leijten and La Forge are the only two remaining members of the " Victory " away team not to have disappeared . Act One . La Forge and Leijten go to Ten Forward to reminisce about their days on the " Victory " and catch up with events , such as Leijten discussing on how she almost married Paul Bogrow , a man she could barely stand . Helmsman reports that they have entered the Tarchannen system , where the crew finds the shuttle . Worf hail s the shuttle but Hickman doesn ' t respond . The shuttle approaches the planet too fast and burns up in the atmosphere . Sensor s detect two more shuttlecraft on the surface , but no life sign s . Picard orders an away team to investigate . On the surface , the away team discovers the shuttle " " , which Mendez stole from the . While La Forge checks out the shuttle , Leijten finds strange footprints in the sand , and she moves toward them for a closer look . Worf tells Riker he has a feeling they are being watched . La Forge returns with chilling evidence : a torn Starfleet uniform . La Forge notices that Leijten is missing . The other members of the team spread out to look for her . When La Forge follows some footsteps in the sand , he finds her staring blankly into the darkness . She claims she can feel the missing crew ' s presence . She starts to shake violently , screaming , as La Forge calls up a medical emergency beam - out . Act Two . Leijten wakes up in a bed in sickbay . Dr . Beverly Crusher reports that her blood chemistry is off and that she ' s had a histamine response to something she can ' t identify . Leijten feels compelled to return to the surface but Crusher orders her to stay on the " Enterprise " until she can find out what is wrong . Leijten protests , but Picard confirms the order . Leijten and La Forge are walking in the corridor when Leijten ' s hands start to tremble . She expresses the fear that whatever is happening to the away team members is happening to her . On the bridge , Data examines evidence collected from the survey . He has found some alien s that don ' t belong to any known Tarchanen lifeform . While Data attempts to find a match for the cells and footprints , La Forge and Leijten decide to go through the mission log to see if there is any commonality they missed that would make the crew return to Tarchanen III to be abducted . As they examine the logs , Leijten becomes agitated and demands to go back to the surface . As she leaves , she begins to shake uncontrollably and collapses as he and Lt . Wallace rush over to help . La Forge notices a strange blue growth pattern on the back of her neck and that her fingers have grown together . Act Three . Leijten is in sickbay with the lights dark , as she has developed an extreme sensitivity to light . The strange growth patterns now cover most of her body . La Forge comes to visit and comfort her . Crusher discovers that Leijten ' s cells have now changed to match the alien cells found on the surface . Crusher theorizes that the missing crew were not abducted , but transformed into a different species . Crusher informs La Forge that he will most likely be next and that he should stay in sickbay . He insists that he needs to work on the investigation and leaves , recommending that the computer monitor him . He returns to engineering and begins to thoroughly examine the logs again . He runs several scans on the data , but nothing comes up . Data arrives to ask about his progress and if he can help , but La Forge is exasperated and says he just needs to go over it again . Meanwhile , Leijten ' s body makes more drastic changes . Alyssa Ogawa shows Crusher that her body can simulate light in a radiant reaction . Furthermore , her body temperature dropped drastically , despite the T - cell inhibitors . Crusher tries to scan her , but the readings are faint . She orders a full genetic analysis . La Forge then notices a slight shadow on the visual log that he cannot identify . He tells the computer to create a holoprogram based on the sensor log data . As he goes to the holodeck he notices that his hand has begun to tremble as well . Act Four . In the holodeck , La Forge uses the computer to remove people and their shadows from the simulation until only the strange shadow is left . He then uses vector analysis to determine the location of the object causing the shadow . He is shocked to discover a Human - sized invisible shape . He then slumps down in pain . The same physical changes that Leijten experienced are starting to happen in his body . In sickbay , Crusher and Ogawa have found a parasite in Leijten ' s thymus which is transforming her body . Not like a normal parasite , it ' s using Leijten ' s immune system to propagate genetic changes to match its own . They have to act quickly , while there is still DNA intact , to help reverse the damage . Martinez comes to assist in the procedure . Dr . Crusher operates on Leijten and removes the parasite in time . She begins to return to normal . She tries to find La Forge , but he has disappeared . The computer reveals the last location of La Forge and Picard sends Worf , Riker and a security detail to the holodeck . When they arrive they see what La Forge saw , and Worf discovers a grisly scene : La Forge ' s torn uniform and his VISOR . Riker steps back as he gazes at the eerie image , thinking that this is what the chief engineer has become . In the transporter room an invisible shape attacks Hedrick , the transporter operator , overrides the transporter lock out and beams to the surface . During the beam - out , the image of what La Forge has transformed into , appears for the moment before the transport is complete . Act Five . With less than an hour left before the transformation is complete , Data develops a method to detect the aliens using ultraviolet light from an emergency beacon , while Hedrick finds the transport location and Riker and Worf prepare their search method . Meanwhile , Leijten has come around , the changes in her hands and face reversed . She wants to find La Forge , and tells Crusher that the process was actually a method of reproduction , a ; they multiply by infecting humanoids with the parasite . She also says she has to go with them to find him , as they won ' t be able to detect him without her . Crusher , Leijten , Riker , Worf , and Data beam down to the surface . They find the nearly transformed La Forge , along with the fully transformed creatures that were once Brevelle and Mendez . The latter two flee , but Leijten was able to talk with La Forge , breaking into the conflict between his Humanity and the metamorphosis trying to win control . Breaking through the fear , he reached out and grabbed Leijten ' s hand and the two embraced , allowing Crusher to beam both of them to sickbay . On the " Enterprise " , Crusher is able to save La Forge , but sadly it ' s far too late to save Brevelle and Mendez . Based on his own experience , he reports that the creatures are unintelligent : operating entirely on instinct . He turns to Leijten and notes that he would not be able to recognize her voice in a matter of minutes . Picard decides that the inhabitants of Tarchannen III should be isolated . He orders warning beacon s placed around the planet and on the surface to warn others of the aliens there . La Forge thanks Leijten for her assistance in helping to find him . He remarks that while he was transformed , he had no idea who Leijten was but somehow he both believed and trusted her . " " Must have been because of all the good advice I used to give you " " , she says . Memorable quotes . " " 49 people gone . " " " " And five years later , the away team that was investigating their disappearances have started to disappear themselves . " " " " Geordi and I are the only two left . " " " " Well , Suz . . . what do you think ? " " " " I don ' t know , but I ' m not ashamed to tell you . . . I ' m a little scared , you know ? " " " " Yeah . " " " " Well , if anyone ' s gonna figure this out , it ' ll be the " Leijten and La Forge Show " , right ? We always were a good team . " " " ( raising his glass ) " A hell of a team . " " " " You ' re worried about Geordi , aren ' t you ? " " " " I am an android ; it is not possible for – " " ( Crusher interrupts ) " " . . . you to feel anxiety . " " " " Starfleet personnel have vanished . Others may be at risk . We must do the best we can to find out why . However , I am . . . strongly motivated to solve this mystery . " " " " Computer , delete La Forge . " " " " I ' ve come back , Geordi . Let me take you back too . " " " " You know , down there , I . . . I didn ' t know who you were and yet . . . somehow , I " believed " you . I " trusted " you . " " " " Must have been because of all the good advice I used to give you . " " Links and references . References . advisor ; ; bioscan ; blanket ; Bogrow , Paul ; Brevelle ' s shuttlecraft ; cc ; cell wall integrity ; chameleon ; " " ; day watch ; DNA ; emergency beacon ; emitter module ; Federation ; Federation supply ship ; foreign body ; gene ; genetic analysis ; EM scan ; histamine ; infrared sensor ; interferometric frequency ; ionizing radiation ; ionosphere ; kayolane ; Malaya IV ; medical tricorder ; mucus membrane ; NCC - 70367 ; NCC - 70367 shuttlecraft ; number one ; palm beacon ; parasite ; photosensitivity ; proximity detector ; sandstorm ; security lockout ; sedative ; sensor array ; spectrographic analysis ; Starbase 112 ; subspace ; T - cell stimulator ; Tarchannen system star ; Tarchannen III ; Tarchannen III species ; Tarchannen system ; thermosphere ; time index ; thymus ; tricorder ; turbolift ; Type 7 shuttlecraft ; Type 15 shuttlepod ; ultraviolet radiation ; vector analysis ; ; viral crèche ; VISOR ; visual recording device ; warning beacon s ; Z - particle