The Crossing (episode)
Enterprise is captured by a ship of non-corporeal beings who wish to trade consciousnesses with the crew's bodies. But these "wisps" may not plan on giving the bodies back...

Summary

Teaser 
 is being chased by an unknown vessel approaching at warp 6. Apart from observing its size to be over five hundred meters wide, the Enterprise crew is unable to tell anything more about it – the hull has an unidentified composition and there is no warp signature. Attempts at contact fail, as the ship probably doesn't have any transceiver. As the alien ship gains on Enterprise, it opens a forward bay hatch and traps Enterprise inside.

Act One 
Captain Jonathan Archer immediately orders tactical alert, only to discover that all weapon systems and engines have gone offline. Looking outside, the crew sees a spacious hall with blue wisp-lights dancing below the ceiling. Learning there are no detectable lifeforms on the ship, Archer takes Lieutenant Malcolm Reed and Commander  to investigate the alien ship's interior. 

As the away team, clad in EV suits, leaves the  they detect change in the atmosphere – from one composed mostly of helium, it turns into Human-breathable nitrogen and oxygen mixture. Even though their scanners still don't detect any lifeforms, watching the wisps they grow certain they're dealing with sentient beings. Soon one of the wisps approaches them and, through his helmet, enters Trip Tucker's head. It emerges a second later, its color changed from blue to golden. Tucker remains conscious, however he is unresponsive and seems disoriented. A little later, the golden wisp returns, switches back with the blue one, and Tucker regains control over his body. Bewildered and not sure about what happened, he recalls watching the away team from above and also a very realistic vision of him swimming at Tarpon Springs with his former girlfriend Lisa, even though they're 150 light-years from Earth. 

Archer and Reed immediately take Tucker back to Enterprise, where Dr. Phlox examines him, but finds nothing out of the ordinary. Although Archer is still worried about the incident, he tells Tucker to work on activating the engines. He also asks Reed to bring the weapons online as soon as possible.

Act Two
Back in his quarters, Archer discusses their current situation with T'Pol. She tells him to consider that the creatures might not be hostile, but Archer remains skeptical. She also informs him of Hoshi Sato's unsuccessful attempts at communication and the uneasiness of the crew.

In engineering, Tucker is working at the main console when the wisp returns and enters his body again. He exits engineering, leaving behind engineer Michael Rostov puzzled by his strange behavior. Rostov immediately informs Archer about the incident and they find Tucker shortly thereafter in the mess hall, enjoying various types of food. Confronted by Captain Archer, the creature admits switching places with Tucker, but assures he will be back. It also explains that they're explorers, just like the Enterprise crew, that used to be corporeal beings generations ago and are trying to learn more about their ancestors' way of living. At Archer's request, it releases Enterprise from the alien ship's bay and soon after the golden wisp returns, returning Tucker back to normal. Again he tells them about reliving some wonderful memories during his time in non-corporeal form and says that "they" offered everyone in the crew to try the experience. Archer however is apparently more worried and orders Reed to take Tucker to sickbay.

In his quarters, Archer ponders his distrust of this strange lifeform when he's interrupted by the entrance of visibly agitated Dr. Phlox. Just a moment ago, one of the wisps tried to enter Phlox, but without success, probably due to Denobulan physiology being incompatible with the beings.

In the armory, another wisp infests Reed, who at first tries to shoot it with a phaser, but to no avail. The creature in Reed's body makes several lewd remarks to a female crewman in the turbolift, and when the confused woman leaves the lift, he makes his way to T'Pol's quarters. After voicing Reed's opinion about T'Pol being the most beautiful woman on board, he makes some rather crude advances towards her. She at first thinks him drunk, but soon realizes what happened and summons Archer and a security team. As this creature isn't as cooperative when asked to leave Reed's body, Archer orders him locked in Reed's quarters.

Hearing the grim news, Tucker and his engineers hurry to get the engines working. Tucker finds that Rostov had also been infested and soon the bridge is flooded by reports of similar incidents throughout the Enterprise. Archer orders the security teams to have anyone acting strange confined to their quarters, then asks T'Pol and Phlox to find a method of detecting infested people.

Act Three
The engineering team manages to get the impulse engines back online, but Archer decides not to move until they find a way to bring back Reed and the others. Meanwhile, Phlox and T'Pol discover raised levels of acetylcholine in the autonomic nervous system of the possessed people and program scanners accordingly, thus gaining ability to identify infested crewmembers.

On his way to a warp nacelle, Travis Mayweather spots a wisp approaching him and starts running away. During his frantic escape, he accidentally finds out that the wisps are unable to penetrate the osmium alloy shielding of the catwalk. Hearing about existence of such safe area, Archer immediately orders transferring command functions and evacuating all non-infected crew to the catwalk. Despite this ray of hope, there is another grim discovery: Hoshi Sato has been infested and tries to once again convince Archer for the crossing.

It turns out that 58 non-affected crewmembers retreat to the catwalk, leaving outside Dr. Phlox (who is immune to possession) and 24 infested crewmembers locked in their quarters. With situation more or less under control, T'Pol asks the captain to allow her to leave the catwalk. She wants to discover more about the creatures and their intentions by coming into contact with one of them. She believes that with Vulcan mind discipline she should be able to resist the possession. 

Meanwhile, Sato's resident summons Dr. Phlox to her quarters, saying she has a broken leg and requires medical attention. When he examines Sato and finds she is in fact unharmed, the alien possessing her violently attacks Phlox, screaming she needs to get the rest of the crew. He manages to subdue her using a hypospray and goes to assist T'Pol.

T'Pol carries out her plan and discovers the true motives of the aliens. It turns out they can't survive in space without the ship, which is breaking down – and they're unable to repair it. They need to find corporeal hosts in order to survive, and 82 of them are trying to get Enterprise crew as their hosts. T'Pol also reveals there are hundreds of these creatures on their ship, hunting for more vessels with compatible hosts.

Act Four
Captain Archer is adamant about saving the infested crewmembers, so he, T'Pol, and Phlox decide to try flooding the ship with carbon dioxide. As T'Pol learned that dead bodies can't serve as the aliens' hosts, suffocating the possessed will force wisps to leave. Purging CO2 at the right moment will give Phlox enough time to resuscitate the victims. Phlox puts on an EV suit and starts working on the ventilation system, with Archer and T'Pol giving him instructions via communicator. 

However, it turns out that one of the wisps has found its way into the sealed catwalk, and once again possessed Tucker. When he hears about the plan, he storms out, beating Mayweather who tries to catch him. Tucker finds Phlox and tries to stop him, but after short struggle, Phlox opens the CO2 valve and Tucker falls unconscious. When the gas gradually fills all decks and the infested people suffocate, the wisps escape their dying hosts and return to their own ship.

When the last wisp leaves, Enterprise goes to full impulse speed, but the wisps aren't willing to give up. They move to recapture Enterprise, with their ship's maw wide open. However, it seems that Reed and his team managed to get at least some weapons working and two spatial torpedos fired into the ship's open hatch tear it apart from the inside.

On the Enterprise, Phlox revives Tucker (who remembers only he had "just been at a barbecue") and takes him along, stating that they "have a lot of doors to unlock".

Memorable quotes
"It's like we're in a belly of the beast."
"We have no reason to believe their motives are hostile."
"They're holding my ship hostage."
"We don't know that."
"We don't? Look out there! You see any stars? Our engines are offline, our weapons... seems kind of hostile to me!"
"I suppose it depends on how you look at it."
 - Archer and T'Pol

"Something smells funny."
 - Archer, to T'Pol on the Wisp's true intentions

"Are you a female?"
"Sir?"
"Your gender... you are a female, correct?"
"Last time I checked."
"I am a male!"
"I'm aware of that, Lieutenant."
"There seem to be a number of anatomical differences..."
"Sir!"
 - Wisp-alien in Malcolm Reeds body, talking with a female crewman

"Are you aware that you are the most attractive woman on board this ship?"
 - Wisp-alien in Malcolm Reeds body, to T'Pol

"If we are to engage in mating, it would be easier if you disrobed."
 - Wisp-alien in Malcolm Reeds body, talking with T'Pol

"Enough! Humans don't like doing things without their consent!"
 - Archer, to the Wisp inhabiting Reed

"I understand how you may be frightened by all this. Losing your substance, existing as perceptive energy. But you'll be grateful once you've made the crossing, I promise you."
"We're kind of fond of our substance!"
 - Wisp-alien in Hoshi Satos body and Archer

"I've reached the access tube, captain."
"Good. Now pull off the panel."
(Phlox strains to remove the panel.)
"It's not coming off."
"It'll come off. You just need to use a little muscle."
(He tries again, grunting, but the panel still won't come off.)
"I've used every muscle I've got – it won't budge."
"Try using your foot for leverage."
(Phlox tries one more time and the panel comes off, sending him tumbling backwards with the panel in his hands.)
"Good suggestion."
 - Phlox and Archer

Background information
 This is the first appearance of Crewman Michael Rostov since , in the first season of Enterprise. This episode also marks the final appearance of Rostov on the series, although he is later mentioned in the third season episodes  and .
 The fact that the secondary bridge was left in the catwalk after the episode  may demonstrate the original Starfleet concept of a battle bridge or auxiliary control center.
 This episode was nominated for an Emmy Award for Outstanding Special Visual Effects for a Series.
 This episode marks the first chronological appearance of a non-corporeal lifeform.

Links and references

Guest Stars 
 Joseph Will as Michael Rostov

Co-Stars
 Matthew Kaminsky as Crewman #2
 Steven Allerick as 
 Alexander Chance as Crewman #1
 Valarie Ianniello as Female Crewman

Uncredited Co-Stars 
 Adam Anello as operations division crewman
 Jef Ayres as Haynem
 Richard Bai as command division crewman
 Brian Bennett as operations division crewman
 J.J. Bennett
 Solomon Burke, Jr. as 
 Mark Correy as Alex
 Kevin Derr as command division officer
 Hilde Garcia as Rossi
 Robert Garcon
 Glen Hambly as operations division ensign
 Scott Hill as Hutchison
 Aldric Horton as operations division crewman
 Baron Jay as operations division crewman
 Roy Joaquin as science division crewman
 John Jurgens as command division crewman
 Andy Keith
 Aouri Makhlouf as medical crewman
 Marnie Martin as operations division crewman
 Michael McAdam as command division crewman
 Marlene Mogavero as operations division crewman
 Bobby Pappas as operations division crewman
 Monika Spruch as science division crewman
 John Wan as operations division crewman
 Mark Watson as operations division crewman

Stunt Doubles 
 Shawn Crowder as stunt double for Connor Trinneer
 Vince Deadrick, Jr. as stunt double for John Billingsley
 Karen Sheperd as stunt double for Linda Park

References 
access tube; acetylcholine; alloy; anatomy; atmosphere; atmospheric recycling manifold; autonomic nervous system; barbecue; blue; bread; camera; carbon dioxide (); carbon dioxide tank; ; catwalk; Celsius; centimeter; central ventilation; clean bill of health; Cole; corporeal (aka corporeal being); crossing; deuterium injector; deuterium pump; dilithium matrix; Earth; EV gloves; EV suit; explorer; fine motor skills; Florida; gender; girlfriend; God; hand scanner; helium; hull plating; impulse engine; leaf; leverage; ; logic; mating; meter; neural pathway; New Zealand; nitrogen; non-corporeal being; November; osmium; osmotic filter; oxygen; phase cannon; power grid; physiology; recycling manifold; sexual reproduction; ; ; snow-sailing; spare ribs; spatial torpedo; subspace; support plate; swimming; tactical alert; Tarpon Springs; temperature; transceiver; transfer line; ; turbolift; Vulcan; Vulcan database; warp engine; warp coil; warp nacelle; warp signature; wisp; wisp's ship; xenon

External links 
 
 
 

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nl:The Crossing
Crossing, The