A transporter incident results in Ensign Ro and Commander La Forge being invisible and presumed dead by the Enterprise crew.
This is an enjoyable episode with an entertaining concept and decent character moments.
The plot works in as much as you do not question the scientific basis of the main concept. Much like the movie Ghost, it is cool to see characters involved in scenes where others cannot see them and more fun is that it is a sci-fi context. It all builds to pretty strong resolution in Ten Forward that applies a fairly light hearted tone to the suspense, considering it involves their presumed deaths.
The paring of Ro and Geordie is great. Especially as they are written with two distinct outlooks on the situation. Geordie's arc drives the episode towards a resolution, whilst Ro is more reflective and together they balance the story nicely between plot and characterisation. Michelle Forbes gives another charismatic performance and combined with the writing, she helps develop the character beyond the hard-headed maverick previously depicted. She shows some decent moves in one cool fight scene and Forbes generally stands out, as she does in most episodes.
Other characters have decent moments, such as Riker (who gets his trombone out), Data, Worf, and Picard. All actors are in good form.
Visually it works brilliantly, showcasing a great use of bluescreen effects that make the key scenes work so well. You could question why they never fall through the floor, but when you have Ro Laren on screen for a large part of an episode, who cares?
I almost forgot to mention the Romulan aspect of the story, which is fairly good, but makes you question some of the actions of the Enterprise crew in not treating them with a bit more cynicism.