I love this episode, because while it's full of callbacks to previous episodes it also does a pretty good job of standing alone. It also lays in some foreshadowing for the future.
I'll start with the B plot, which is slight but amusing: Garibaldi's building a motorbike. It's an Earth antique (although roughly contemporary with when the show aired). He's sourced parts here and there, but his main problem is the handbook's in Japanese.
Enter Lennier. Always adorably eager to please, and passionate about history, he offers to study the handbook. Garibaldi gives it to him, allows access to his quarters, and leaves Lennier to it as he gets sidetracked by the main plot. Lennier is book smart but not people smart, so most of the humour comes from him failing to read Garibaldi's social cues when he's over-stepping.
This plot now only works if you imagine the internet was never invented. Otherwise Garibaldi would have access to the 24th century equivalent of YouTube tutorials and hobby-related social media. Someone, somewhere, would have translated the handbook already. Or you can imagine he's the kind of bloody-minded enthusiast who wants to do things the old-fashioned way, which would be in character for him.
The reason Garibaldi's distracted is because there are a couple of shady characters poking around claiming to be military contractors. They're asking questions about Commander Sinclair, and last time shady characters took an interest in him he was abducted, so Garibaldi wastes no time in tracking them down. They're actually Colonel Ari Ben Zayn from Earth Internal Affairs (the Eyes of the episode title) and his assistant Harriman Gray of Psi Corps, on the station to investigate the command officers.
As soon as they're rumbled (and they weren't exactly being subtle) Zayn starts throwing his weight around. He tells Sinclair he's going to have Gray telepathically scan all of the command staff under new regulations, and commandeers Garibaldi to his staff. Ivanova, who's been previously seen to have issues with telepaths, is not happy but Sinclair talks her down by insisting on checking the regulations for himself. Garibaldi is also not happy, and tells Zayn as much. When ordered to personally compile the file of the command staff, including classified data, he also investigates Zayn and Harriman asking the computer to include "the usual sources" suggesting not only that he's looking at more than their Wikipedia page but also that this sort of check is routine.
While Garibaldi's compiling, Harriman Gray is - apparently having no sense of self-preservation - trying to make friends with Ivanova. He visits the observation deck on the pretence of looking at the stars and tells her that he's no different that she is - a late bloomer, his boyhood dream of being a combat pilot was shattered when his telepathic abilities manifested when he was 16. As such he respects Earthforce and the people who serve in it. He tries to reassure her that his scan will only look at her thoughts relating to her duty, but she's having none of it.
The reasons for her refusal to be scanned comes at the episode's low point, a heavy-handed dream sequence in which she sees her mother being restrained by characters in theatre masks and given a telepathy-supressing injection. "Only one way out" Sofie says, alluding to her suicide. She looks up at Ivanova wearing her face and repeats herself, and Ivanova wakes up screaming. She later ties to resign, but Sinclair refuses to let her.
Gray seeks her out again to chat, and inadvertently picks up her surface thoughts about the station's resident telepath Talia Winters. Ivanova berates him for the breach of privacy and he apologises, noting his surprise she was able to tell he'd done it. When he posits it must be because of her mother's contact prior to being discovered Ivanova lashes out again. In tandem with the dream it suggests Ivanova is protecting more than just her honour in her refusal to be scanned.
Zayn calls Sinclair up to be scanned, who uses interpretation of the rules to point out to Zayn why it's not allowed. Given Sinclair's previously shown himself to be a formidable opponent where politics and regulations are involved, it's amazing no one saw this coming. The new regulations Zayn's relying on don't allow for blanket scanning for loyalty checks, only to investigate specific charges. However when Sinclair reaches the end of his patience at Zayn's interference in the running of the station and tries to end the interview, Zayn relieves him of command and charges him with insubordination. Now, he has to submit to a scan.
Garibaldi's investigation reveals that Zayn and Psi Cop Bester are friends, and that Zayn was much further up the list - top ten - of candidates to run Babylon 5 than Sinclair was. Bester, previously seen in "Mind War", had implied he'd seek revenge on Sinclair for his previous lack of co-operation. Sinclair uses this information to plant doubt in Harriman Gray prior to the scan, which feeds doubts Gray has shown himself earlier in the episode. Primed to pick up stray thoughts from Zayn during the Sinclair's questioning, Gray can't help but do so when Sinclair rattles Zayn enough to lose control. Between them, they knock Zayn out and normality is restored.
Garibaldi returns to his quarters to find Lennier's finished the bike. Garibaldi's gutted, and Lennier mortified at not realising Garibaldi wanted to build it himself. All is forgiven when Lennier reveals he's equipped it with a Minbari power source and it's rideable.
There are some great character and worldbuilding touches in the episode, that help to create the feeling that it exists as part of a wider story - in contrast to Star Trek's story-of-the-week method which often felt like each episode hit the reset button. Throughout there are hints as to the growing problems on Mars, and Lennier only visits Garibaldi as Delenn wants to request additional security for her friend Shaal Mayan, who will be visiting again after being attacked in "The War Prayer". When Garibaldi tracks down Zayn and Gray, Gray's alone and we see him pull on gloves before he allows access, showing us he's a telepath. There are calls back to Ivanova's backstory, and Sinclair's, as well as the more obvious moments where Zayn questions Sinclair's command decisions.
However all of these moments are given context, so it doesn't matter if previous episodes have been missed. In this way I think it's one of the more successful episodes, that can stand alone while still working as part of a larger whole.