"The Loss" is the 84th episode of the American science fiction television series Star Trek: The Next Generation. The tenth episode of the fourth season.

In this episode, the USS Enterprise becomes trapped within a field of two-dimensional lifeforms, while Counselor Troi struggles with the sudden unexpected loss of her telepathic abilities.

Traveling through deep space, the Enterprise stops to investigate an odd phenomenon that appears like phantom images. Meanwhile, ship's counselor Deanna Troi experiences disorientation as her empathic abilities suddenly cease to work.

They discover they cannot resume course as the Enterprise is caught up in a group of two-dimensional lifeforms.

Without her powers, Troi suffers a tremendous sense of loss, and goes through several classic psychological stages including denial, fear and anger. Ultimately, despite the reassurances of her friends, she resigns as ship's counselor, believing that without her empathic abilities, she cannot perform her duties.

Commander Data and Commander Riker realize the two-dimensional creatures are heading for a cosmic string, with the Enterprise in tow, and once they reach the string the ship would be torn apart. Realizing Deanna's loss and the ship's predicament are somehow linked, Captain Picard pleads with her to try and communicate with the strange creatures.

After attempting to warn the creatures of the danger posed by the cosmic string, Troi posits that they are seeking out the cosmic string in much the way a moth is drawn to a flame. Working from this hypothesis, Data simulates the vibration of a cosmic string, using the Deflector Dish at a position well behind the Enterprise. The simulations eventually causes the creatures to briefly reverse their course, breaking their momentum long enough allowing the Enterprise to break free.

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