“Marvel’s Agents Of S.H.I.E.L.D.” Season 2 episode 5 was jam-packed with action and suspense. Skye (Chloe Bennet) developed a new theory on Coulson’s (Clark Gregg) alien writing, Simmons' (Elizabeth Henstridge) cover was blown and Bobbi Morse, a.k.a. Mockingbird (Adrianne Palicki), was introduced. Plus, Skye might be an alien. This was definitely not an episode to miss.

In the episode, Coulson was carving on his desk, and Skye saw it. She asked to follow up with his source about the carvings, and Coulson refused to give her information.

“Keeping her in the dark won’t end well,” May (Ming-Na Wen) warned.

Skye went down to get information from Ward (Brett Dalton), but he turned the conversation to her father. He told her that his information on his father came from Raina (Ruth Negga) and Skye disregarded the reveal. Raina was crazy, evil and played them all. She couldn't trust her as a source. She was really there to talk about the carvings. Ward said that he saw them before. Garrett (Bill Paxton) had written them everywhere before his death.

“Garrett was long gone once the writing started, and whatever took his place—I don’t think it was meant to survive,” Ward said.

Skye went to Coulson and he admitted that it was his writing. Seeing Garrett’s writing triggered his own carvings, but Skye wasn’t triggered. He wondered why she didn’t react.

“Yeah right, like I’m an alien. … Hold on, are you saying I might be an alien?” she asked.

Skye’s freak out was interrupted by a call from Raina. She needed to see Coulson.

Raina has apparently been working for the Doctor (Kyle MacLachlan) for years—possibly her entire life. Raina is afraid of Daniel Whitehall (Reed Diamond). He threatened to kill her if she didn’t get the obelisk to him.

“I’m a man trying to put my family back together,” he said.

He got angry and started to strangle her. It was implied that this was a pattern for him.

“If Skye sees you like this you’ll lose her forever,” Raina warned.

She called Coulson and they went to a fancy dinner together. Public meetings were the only way they could talk, but S.H.I.E.L.D. infiltrated the entire restaurant. Raina threatened to blow Simmons’ cover at Hydra if he didn’t give her Skye. She had to take Skye to her father. She knew Skye was there and listening, so she tried to appeal to get her to feel sympathy for her father or Simmons. Skye tried to go out, but May held her back.

Raina gave Coulson two minutes. If her timer ran out, her phone would send Coulson’s photo with an incriminating photo of Simmons to all Hydra agents.

Simmons was using a paper-thin tablet-like device to communicate with S.H.I.E.L.D. She threw it into the trash outside with a message, but Hydra found Simmons’ communication device. Hydra’s security chief Bobbi Morse was looking for a mole. Simmons had another in her desk, but she planted it on her lab partner. Still, Bobbi seemed suspicious of her.

“I want you to keep something in mind, Agent Simmons: Hydra is everywhere,” Bobbi said.

Simmons sneaky efforts were all for nothing, though. Raina’s timer ran out and Simmons’ photo was on every computer at Hydra.

Raina didn’t have a choice. She had to get Skye to her father or risk being killed. Whitehall wanted the obelisk but the Doctor had it and he wouldn’t let it go of it until he was reunited with his daughter. Coulson thought he was in control of the situation, but he wasn’t expecting Skye to go find her father on her own.

Once May looked away, Skye ran to Raina and the Doctor’s headquarters. She kicked down the Doctor’s door and found a photo of him holding a baby, presumably her—but he wasn’t there. Coulson caught up with her and promised to find him. They didn’t know that the Doctor was watching surveillance footage from afar. They found his lab and dead bodies. Skye knew it was her father that killed them. Once the Doctor knew that his daughter thought of him as a monster, he threw down the tablet and drove off.

Back at Hydra headquarters, Simmons had to run from Bakshi (Simon Kassianides), but she ran into Bobbi in the hall. Morse knocked out her agents and helped Simmons escape. Simmons realized that Bobbi was S.H.I.E.L.D.

“Coulson has a plan,” Bobbi said.

Bobbi fought Bakshi and his men and went to the roof with Simmons. They jumped onto an invisible S.H.I.E.L.D. jet piloted by Tripplet (B.J. Britt). Bobbi explained that Simmons was there to get high level information on Hydra's projects while she was sent to find out security details and keep an eye on Simmons. Though they didn’t get all the information that they needed, Bobbi stole Simmons' hard drive to help them a little more.

They went back to S.H.I.E.L.D. headquarters and met up with Coulson, who offered Bobbi a place on the team. It seems like she will accept the offer as she knows plenty of agents. She and Mack (Henry Simmons) go way back and he was excited to see her. However, Hunter (Nick Blood) was not happy at all. He told her he liked her better blonde, and they immediately started bickering.

Triplett asked May why there was so much tension. Bobbi was Hunter’s ex-wife, the one he consistently told stories about. The whole team knew that he hated his ex-wife because he couldn't stop talking about how much he despised her. They might not have expected her to be so likable.

Meanwhile, Simmons went to see Fitz (Iain De Caestecker). Earlier in the episode, he finally acknowledged that his hallucinations of Simmons were unhealthy. It seemed like he was healing. So he was a little shocked to see Simmons.

“Is that really you?” he asked.

“Of course it is. Who else would it be?” she said. She obviously didn’t realize that he had been talking to a hallucination of her for months.

Skye and Coulson were reconnecting as well. He was bringing her in on everything. He revealed the hidden wall with his writings. Skye had a new theory about the writing: it could be a map.

The ominous end scene took the audience back to Hydra. After being infiltrated by multiple S.H.I.E.L.D. agents, the Hydra facility was being dismantled, but the Doctor came in before they could go. He brought Whitehall the obelisk (called the Diviner in its native language). The Doctor promised to teach Whitehall how to use it if he helped kill Phil Coulson.

“Marvel's Agents Of S.H.I.E.L.D.” Season 2 airs Tuesdays at 9 p.m. EDT on ABC. How do you think Fitz will react to Simmons’ arrival? Sound off in the comments section below!