The episode opens in Bruges, Belgium on the Haly Circus, which we know is the circus that Dick Grayson and his family The Flying Graysons were a part of, until his parents were killed when a criminal sabotaged their trapeze act.  Meet their new feature attraction, The Daring Dangers– Dan and Dawn Danger, the trapeze artists, Diane and Dane, the archers and strong man, the barrel-juggling Dean!  Of course we quickly realize that this is Robin, Miss Martian, Artemis, Red Arrow and Superboy in silly red and white circus outfits.  Just as ringmaster/circus owner Jack Haly announces that they are performing without a net, Robin/Dan misses Miss Martian/Dawn’s hands and goes plummeting!  “Robin!” gasps Miss Martian, cluing in anyone who hadn’t quite put it together yet.

Telepathically, Robin tells everyone not to blow their cover as he falls to possible death.  Superboy/Dean flings a barrel upward, upon which Robin lands and rides it back up as Miss Martian/Dawn swings back out to catch him.  Once more, he falls short, but she telekinetically raises him the extra inches and grasps his hands.  Once they land, he scolds her slightly for using her telekinesis, but she admits she’s been using it all night, because she isn’t an acrobat on par with Robin.  He admits he isn’t feeling well and mentions that a flu like sickness is working its way through everyone in the circus.

In a flashback, Robin explains their mission.  A rash of robberies at technological facilities across Europe, corresponds with performances by the Haly Circus.  Red Arrow invites himself along on the mission, to keep an eye on the three possible “moles” that have infiltrated the team, Superboy, Artemis and Miss Martian.

Back to the circus, Miss Martian must help a weakened Robin backstage.  A fire-eater, dressed like the devil, scrambles to find his torches before running out to take center stage.  Two acrobats confront Jack Haly.  They used to be the headliners of this circus before the Daring Dangers showed up.  Haly defends his replacing of them by pointing out that they missed a show in Paris.  “Carlo was sick.  He’s better now!”  There’s that darn sickness again.  The two acrobats are suspicious of the Daring Dangers.  “They say they’re brothers and sisters, but they don’t even look alike.”  (Isn’t Artemis half Asian?)

A white haired man then confronts Jack.  It’s King Farraday, one of DC’s leading spy characters.  He has also noticed the connection between the circus’ shows and the robberies at the tech firms.

The team later stakes out a tech facility in Bruges and spot someone with serious acrobatic skills breaking in.  Superboy attaches one of the patches that Lex Luthor gave him that negate his human DNA, granting him full Kryptonian powers.  With his X-Ray Vision, he spies the robber in a warehouse and the team confront him.  Artemis quips, “Acrobatics won’t get you out of this.”  He pulls out a torch and blows fire on them, igniting boxes of live ammunition!  The building explodes!

The kids miraculously survive.  Superboy, all roided up on the patch wants to go after the crook, but Robin reminds him of Miss Martian’s weakness– fire.  Superboy snaps back to reality and takes Miss Martian to safety.  Robin orders Artemis and Red Arrow to find the crook before nearly collapsing from his flu.  The two archers opt to let the criminal escape and get Robin to safety as more burning debris falls.

Farraday confronts Haly regarding the robbery, but Haly says he did a bed check to ensure all his performers were in their bunks.  Artemis comments, “Well we sure weren’t.  And if he’s lying about us…”

The kids know they dealt with an acrobat and a fire-breather.  Robin pulls up security footage of other robberies and it shows that a high-wire walker and a strong man also played parts in thefts.  When the team suspects Jack Haly as being the mastermind, Robin jumps up agitated and yells, “I told you to keep an open mind!” before storming out.

Miss Martian suggest she try reading Haly’s mind, but Red Arrow says he doesn’t trust her to do it without being detected.  Superboy angrily accuses him of simply not trusting them.  Red Arrow points out that he has reason not to; Miss Martian and Artemis have both been caught in lies and Superboy may be programmed by Cadmus and not even know it.  Miss Martian pulls an angry Superboy away, while Artemis tells Red Arrow that any of them would give their lives for the team.

Robin goes for a walk in the snow and finds a Flying Graysons poster hanging up.  He then gets a call from Kid Flash, who tells him he spoke to Red Tornado and knows they aren’t on an official mission.  Robin says he is trying to help Jack Haly as a friend.  Kid Flash references Robin’s past as a member of the circus and questions why he didn’t bring him in on the mission, since he knows about Robin’s past and the others don’t.  Robin explains that that is exactly why he didn’t invite him.  “I didn’t want my best pal questioning my objectivity.”  Kid Flash replies, “Dude, that’s what a best pal is for!”

After their last performance in Bruges, the circus is headed to Geneva.  A roustabout named Ray offers to help “Dawn” (Miss Martian) with her bags, but she says she’s fine and suggests he helps some of the other performers who are suffering from the flu that’s going around.  Jack orders everyone on board.  He seems in a hurry.  Later on the train, Artemis notices that Robin seems to be feeling better.  Unfortunately, Miss Martian is now afflicted with the flu!  “Who knew a martian would be susceptible to a human virus,” she muses, to which Robin replies, “H.G. Wells.”  Cute!  M’gann says the illness came on suddenly.  Robin says his sickness did as well, after Ray rubbed his head for luck.  Superboy points out that Ray touched Miss Martian before they boarded the train, when he was asking if she needed help.

We have a suspect!  Robin/Dan asks Jack how long Ray has been with the circus, to which he says “Since the start of the European tour.”  The kids, including M’gann, rush to find Ray.  But after they leave, Jack morphs into Ray!

They don’t find him, but Red Arrow points to a box of elephant food and asks if there is an elephant on this tour he didn’t know about.  Robin replies, “Not on foreign tours.”  Red Arrow examines the box and discovers ashes from the fire in the factory in Bruges.  Artemis finds a Ray mask under his bed!

They split up and Robin finds Jack bound and gagged in his room.  When he tries to communicate telepathically with Miss Martian, it doesn’t work.  He contacts “Dawn” via communicator and she says she thinks the flu has knocked out some of her powers, including her telepathy.

In the dining car, Superboy confronts a harlequin wheeling a large box.  He puts on another Luthor patch and spies a sophisticated machine in the harlequin’s box.  The harlequin then telekinetically hurls all the tables and chairs in the dining car at Superboy and flees.  Superboy follows him onto the roof of the train.  Robin joins them and identifies the clown as The Parasite, and he’s stolen Miss Martian’s super abilities.  He also explains there is no “flu” going around.  The weakness and sickness is a result of The Parasite stealing the various abilities of the performers in order to commit his robberies.  The other heroes arrive and the Parasite reveals his true form.  He remarks that he was only trying to steal “Dawn’s” trapeze skills.  “Imagine my surprise when she tasted like Martian Manhunter.  She made a lovely appetizer but guess who I want for my entree.”  Telekinetically, he seizes Superboy and draws him to him, draining his powers. He blasts Artemis and Red Arrow with Heat Vision, frying their bows.  He flies off, but Robin leaps after him.  Parasite knocks him down and sends him flying.

Miss Martian grabs his hands and Artemis and Red Arrow help her pull him back onto the roof of the train.  Robin then points out that Parasite stole more power than Superboy is even supposed to possess.  “Heat Vision?!”  None of them know about the patches Luthor gave him last episode.  Superboy mumbles an explanation, that he has the genetic potential for the power.  “That must have been enough.”  The rest of the team departs and leaves Superboy on the roof alone.  He peels off the spent patch and looks at the box of patches in his hand.  (I suspect a Jessie Spano “I’m so excited!  I’m so excited!  I’m… So… Scared!” moment is coming soon.)

Robin reveals that he managed to pickpocket The Parasite and shows the others a flash drive.  He hacks it and discovers that all of the tech the criminal has stolen, on orders from Intergang, are the makings of a black hole generator.  Red Arrow mentions that a particle accelerator is needed and Robin points out that there is one in Geneva, the circus’ next stop.

Red Arrow pulls out a back up bow and says that he and Robin alone should pursue The Parasite.  Artemis whips out a crossbow and says he wasn’t the only one who brought along a backup.  Suddenly Superboy appears, punches the wall and announces that his powers have returned.  “I guess Kryptonians recover faster than Martians or humans.”  Or maybe I used another steroid patch.  Even weakened, Miss Martian also insists on going along.

Once the team has picked up on Parasite’s trail, they rush after him, leaving Superboy to remove his fried patch and once more replace it with a fresh one.  (I’m so excited!)

The Parasite puts the device together, mentioning it would have been easier if he still had his flash drive and fires it up, threatening to wipe out Geneva.  The team is cautiously observing him and deciding what to the best course of action is, when roided-up Superboy snarls and charges in, fists flying.  The Parasite grabs him with Miss Martian’s telepathy and pulls him forward, but Superboy slugs him.  Parasite punches back, then knocks him around before clutching him and draining more of his power.  “How do you do it, kid?  Even Superman never recharged this fast.”  (I’m so excited!)  He then tosses him aside.

Miss Martian confronts him.  She avoids his clutches and trips him, then Red Arrow ensnares him in a foam trap.  Robin attempts to override the doomsday device, but Parasite frees himself enough to blast heat vision at him.  Then Artemis strikes, tricking him into igniting a flammable gas and being engulfed.  Miss Martian explains that by draining her powers, he got her weakness as a side dish.  As he collapses in the flames, she teases, “Poor baby.  Something you ate?”

Robin disarms the black hole machine, as King Farraday enters and takes Parasite into custody.  Artemis helps Red Arrow to his feet.  Now that he has seen them in action, he apologizes for being suspicious and naively declares, “There is no mole.”

Later on, Jack thanks “Dick,” to which Robin nervously replies, “It’s Dan… Dan Danger.”  Jack reveals that he’s known that “Dan” was always Dick Grayson, because of his trapeze skills and form.  He asks for a favor, one last performance.

Well, we all know things aren’t going to go as smoothly as everyone seems to think.  Obviously, there’s still a mole, but I don’t think it will be any of the usual suspects.  Sure Superboy is a clone programmed by Project Cadmus with half of Lex Luthor’s DNA.  Miss Martian is secretly a white Martian, who are usually vicious and evil.  Artemis is the daughter of two criminals (one seemingly reformed).  Also, if you’re familiar with the comics, ONE of the team members fathers a child with one of their enemies.  The least likely (on the cartoon) suspect, actually has the highest motive, if you think about the source material.

It’s only a matter of time, before Superboy’s new addiction causes serious problems.  I hope this occurs sooner than later.  We’ve seen similar storylines before.  (I’m… So… Scared!”)  How much more can they add?

This series relies on its characters and their bond to one another.  Just like in the comics, Robin went through efforts to hide his identity and past from his team, but eventually he came clean with them.  And for such a famous character, his role on Young Justice is sometimes downplayed to showcase the newer, less known characters.  It was nice to get a showcase for him this episode, with plenty of references to his past.  But all the characters included got nice touches and lines of dialogue.  Aqualad was sorely missed, but with such a big cast, occasionally you have to bench one or two.

This is one of the most sophisticated, tense cartoons on right now.  And this was another solid installment.