"We went looking for truth, but found only lies."

-- Syd Barrett

If previous episodes of "Legion" lurched from psychological thriller to sci-fi drama to horror tale, then this week's veers into hard-boiled detective and war-story territory as Melanie Bird sends her troops on a mission -- Division 3 be damned -- to discover what happened to David before he was committed to Clockworks Psychiatric Hospital. It may be the only way to learn why he can't, or won't, awake from sedation and, more importantly, what secrets are locked away in his mind.

Between Melanie and Ptonomy they've arrived at the realization that David can create an astral plane, "something between reality and dream," permitting him to lock away memories, safe from prying eyes, or minds. "It's as if we've activated some kind of guardian," Melanie observes. "There's something in David's brain he doesn't want us to see."

So Kerry, Syd and Ptonomy are given their marching orders. "What was real?" Syd says in voiceover. "That was the mission." It's a relatively straightforward, if not exactly simple, assignment that takes them by public transportation and by foot, from city to woodland to shore, all the while feeling like something existing, well, between reality and dream. It's Syd's narration that anchors their investigation to the real world, even as it conjures images of a fantasy quest.

"We moved through a city of normals, soldiers in a secret war," she says, juxtaposing the real with the fantastic. "We were ghosts in a haunted house, the golem of myth. To the normal we were just superstition, make-believe. Sometimes it felt like that to us, too. To me, I was a woman who couldn't be touched, in love with a man who wasn't there."

But it's not make-believe, Ptonomy assures Syd with at least a trace of certainty as they prowl Dr. Poole's dusty, long-abandoned office, searching for clues to David's past and, quite possibly, the fate of his former therapist. Yet even as Syd reconciles the differences between that physical office and the one she visited in the "invented space" of David's mind, she has difficulty coming to terms with the picture the evidence paints. Although a damaged tape recorder very well could be what her boyfriend used to bludgeon Dr. Poole, Syd sees indication of real memories hidden by fake ones. Perhaps, she suggests, David wasn't stealing drugs or valuables, but instead getting rid of evidence from "a conversation, the one time he said too much." That brings us back once more to the seemingly pivotal question, What did the stars say?

The answer doesn't come, at least not yet. However, we are given an explanation of the relationship between Cary and Kerry, and it's every bit as quirky and touching as we'd hope from "Legion." They're two people who inhabit the same body, and the aggressive, thrill-seeking Kerry only ages when she's on the outside. "He does the boring stuff, OK?" she explains to Syd. "Eating, sleeping, whatever it is you guys do in the bathroom, and I get all of the action. He makes me laugh, and I keep him safe. If that's weird, I'm OK with it." Cary admits to missing Kerry when she's away, and wonders what will happen to her when he's dead.

We also learn a little more about Melanie's husband Oliver, co-founder of Summerland, who it turns out has been stranded on the astral plane for decades, even as his body lies in a vintage diving suit in any icy room deep beneath the compound. When Melanie sees a ghostly diver, she's convinced it's her husband trying to communicate with her. However, Oliver's memories of his wife are fading. Played by Jemaine Clement, he encounters David in the "vast subconscious," and guides him back to his icy home, a swinging '60s bachelor pad where he listens to cacophonous jazz, recites beat poetry, dances and wonders whether "free love is still a thing."

"What's real in this space is whatever you want it to be," he tells David. "So my thinking is, why not wait in style." When David mentions Melanie, Oliver pauses and says, "Melanie. I knew a Melanie once."

Although David isn't willing to give up his secrets just yet, his loved ones have some crucial revelations to offer. Imprisoned by Division 3 and deprived of comfort, his sister Amy finds she shares a cell wall with Dr. Kissinger, the psychiatrist from Clockworks whom she'd been told didn't exist. Expressing guilt for not accepting what she long knew, that her brother wasn't mentally ill but instead possessed incredible powers, she recalls a "sweet" boy who could disappear and reappear, know conversations -- and even thoughts -- he logically couldn't have, and talked to people who weren't actually there. It's in this flood of memories that Amy reveals David's beloved dog King, which appears in so many of his childhood, never existed. "We didn't have a dog," she tells Kissinger.

David's ex-girlfriend Philly, who (surprise!) isn't dead but instead sells real estate, knows some secrets, too. Posing as a couple looking to buy a house, Syd keeps her occupied while Ptonomy peers into her memories and uncovers the location of Dr. Poole's house (well, lighthouse). Unwilling to leave without satisfying her own curiosity, Syd lets on that they know David, leading Philly to acknowledge that their relationship may not have ended so well -- "He was so troubled, you know" -- but, more importantly, his friend Benny contributed to the problem. That's Benny, not Lenny. "Benny was a big guy," Philly says, "smiled a lot, but not with his eyes." But she also has a message for David: "Tell him they're watching."

The Benny revelation seemingly confirms that Lenny is a creation of David's mind, or as Syd theorizes, a product of the alteration of his memory by an outside source. "Lenny, Benny, which one was real?" she wonders. "Or were they one in the same? A man who became a woman, or maybe it was just an illusion." She has little time to ponder that mystery, however, as their search takes them to a picturesque lighthouse that disguises great danger. A fragile, retired Dr. Poole isn't Dr. Poole at all but instead a disguised Eye who reveals himself just as Division 3 soldiers close in and open fire, somehow missing him in the hail of bullets.

Seeing her opening, an eager Kerry dives through a second floor window and takes the battle to her heavily armed opponents. Outnumbered and outgunned, she nevertheless confronts the enemy in one of the more beautifully choreographed television fight sequences in recent memory. Arguably more modern dance than actual combat, the scene cuts between Kerry and the soldiers in the woods and Cary sweeping his lab miles away at Summerland; her every move is mirrored by Cary, with graceful movements giving way to stumbles as the melee turns against Kerry.

Inside, The Eye easily takes out a gun-toting Ptonomy only to find, too late, that he's no match for Syd's touch. Exchanging bodies with her adversary, Syd orders Division 3's soldiers to load the unconscious Kerry and Ptonomy into the van so he -- or rather she -- can drive them to headquarters. It's a quick, clever move by Syd that, of course, doesn't work out as well as she envisioned.

That's because David is waging his own fight on the astral plane. Leaving the relative safety of Oliver's icy "home," David sets out across the vast subconscious, only to find himself in a recreation of his childhood bedroom and face to face with Lenny, or, as says, "Betsy Tough-Love, your mean friend." However, in her desire to be free of the astral plane and to dole out an "I told you so," Lenny may have crossed from "tough love" into downright sinister. Perhaps that's a matter of perception, colored by the knowledge she's not what, or at least who, she seems to be, or maybe she has taken an even darker turn. (Her appearance later over David's shoulder suggests the latter.) Whatever the case, she's not messing around, and gleefully shows David the danger Syd is in, triggering his powers and allowing him to break free of the astral plane and materialize in front of the getaway van. You know, the one that's driven by Syd in the body of The Eye.

The van wrecks, leading to what would be a comedy or errors if not for the life-and-death stakes: David rescues his "girlfriend" (actually The Eye in Syd's body), who then attempts to stab him, only to be stopped by Syd in The Eye's body. In the end, however, Syd and The Eye return to their own bodies, which allows the latter to escape, but not before he shoots Kerry and quite possibly Cary.

Odds and Ends

• Jemaine Clement is, of course, a delight as Oliver Bird, delivering the expected quirkiness but also a little insight into the nature of David's "monster." And his line "Melanie. I knew a Melanie once." is simply devastating when juxtaposed with Jean Smart's Melanie sitting beside the body of her husband, searching for a sign of his consciousness.
• The revelation about King was certainly unexpected, huh? There has to be a connection between the imaginary dog and whatever that creature was in the cage in the premiere episode.