HYDRA’s plan for world domination includes recruiting important SHIELD agents, and they apparently have one already. That agent will be used to get a very special person who is literally as cold as ice.

SPOILERS AHOY

That agent is Gemma Simmons, who has left SHIELD to join HYDRA so that she can do the type of scientific research she’s always wanted. The episode shows her getting ready for a new day, complete with a cheery song and 20 minutes in the elliptical. When HYDRA’s logo is shown on a wall, that’s when the shock hits. She says she’s loyal to science, and also HYDRA because it gave her a job. That’s some serious compromise she had to make.

However, it’s all part of a plan by Coulson to learn more about HYDRA. It’s rather risky, because it’s hard to picture Simmons being evil, or even pretending for undercover work. She’s told to make some friends within the evil agency, and they might notice her.  Coulson wants to stop HYDRA from turning SHIELD agents. Whitehall (Reed Diamond), the ageless HYDRA boss, is already hard at work getting agents through any means necessary.  That includes, in the case of one agent, brainwashing with a device the Alliance would have used on River Tam. He already has a mantra: surrender and you will find meaning. That means obey or die.

Meanwhile, HYDRA is trying to find Donnie Gill (Dylan Minnette), the ex-SHIELD Academy student who had a weather machine last year that caused major damage. Lightning struck him, and he acquired the ability to freeze anything he touches. He had been in SHIELD’s Sandbox before HYDRA took it over, and now he’s trying to hide from them. He thinks Morocco is a safe place, but when he suspects HYDRA agents are close, he winds up freezing people like human statues. Bakshi (Simon Kassiandes), Whitehall’s assistant, figures that Simmons may be used to get Gill to come to HYDRA. She did meet him at the academy, and that could be used. Actually, she is aware HYDRA wants Gill, and tells Coulson about it.

Back at SHIELD, Skye is being trained by May for more intense missions, while Lance Hunter is atoning for shooting May and Skye so that he could get revenge last week. Skye also has her occasional talks with Ward. He tells her that if HYDRA wants a certain person, like Gill, they will try to acquire him… or kill him if he doesn’t join. He says HYDRA will win because while SHIELD agents worry about right and wrong, HYDRA has already taken the shot.

Well, Gill is not ready to be taken. He freezes a cargo ship that was hired to take him to HYDRA, and vows to turn it into one big ice cube. That includes Simmons, who’s been told by Bakshi to convince Gill to join HYDRA.

As the SHIELD crew gets ready to find Gill, Fitz is upset he’s not part of things. He still can’t think like he used to, but he still has ideas. He confronts Ward at Vault 9, and cuts off his air to give him an idea of what Ward did to him. He also tells Ward about the mission, and Ward’s getting worried. Fitz soon learns that Gill was grabbed by HYDRA and also brainwashed.

When Simmons does see Gill, she tries to get him to calm down, while SHIELD and HYDRA agents are battling each other. Hunter almost shoots Simmons when she sees the HYDRA logo on her jacket. May stops him… by shooting him. Bakshi does find Gill, and uses the HYDRA mantra to bring Gill back into its fold. He’s soon freezing the whole ship, trapping May and Tripplet. However, Skye shoots Gill, and he falls into the bay. HYDRA retreats, as does SHIELD. However, Gill’s body hasn’t been found. That means he may be back.

Although HYDRA doesn’t get Gill, Bakshi decides Simmons may be valuable. He tells Whitehall he wants to promote her. If she resists, they can always “make her comply.” It’s a good idea to give Simmons a story arc that keeps her as a scientist, but also challenges her as a spy. However, if she does become “compliant” with HYDRA, and possibly betray SHIELD, will she wind up as damaged as Fitz? That’s something to consider.

Skye is very worried about whether Simmons can fool HYDRA for long, but May tells her Simmons can handle it. Besides, SHIELD has other moles inside HYDRA. Coulson tells Fitz that they need Ward to better understand HYDRA. It’s a necessary evil. Fitz says he wanted to show Ward what he had done, but he is no killer. He’s also told about Simmons’ new mission.

Skye also talks to Ward, and wonders if he’s been brainwashed. He says he hasn’t, which makes her wonder why he turned against SHIELD. He does say that her father is alive, and he will do what it takes to find her. She doesn’t look stunned by this bit of news, but after she leaves, her heart rate tells a different story.

This episode shows what both sides will do to get the upper hand. SHIELD will use unlikely undercover agents like Simmons, and enemies like Ward, to get inside information about the very bad guys at HYDRA. They, meanwhile, will just grab key recruits and persuade them to abandon useless beliefs like freedom and join them. If not, there’s that brainwashing machine and the mantra of surrendering to find meaning. These are ugly weapons for an ugly war.

Next week:  Coulson and May attend an art auction because one of the paintings has some very interesting markings… the kind he draws on a wall every 18 days.

Note: Elizabeth Henstridge talks about Simmons’ undercover role in Entertainment Weekly.

Agents of S.H.I.E.L.D. airs Tuesday nights at 9/8c on ABC. Watch this and previous episodes on ABC’s website.