Tonight's episode of "The Flash" -- which was titled "Monster" -- was all about hiding. The new Harrison "HR" Wells was hiding his true identity from the team. Caitlin was hiding her Killer Frost powers from everyone except her mother. Joe was hiding his feelings from the flirty DA. Julian was hiding his jealousy of metahumans and his noble English birth from Barry. The most obvious moment of hiding came when the apparent metahuman monster that was terrorizing Central City turned out to be a hologram, operated by a teenage boy. As if the team hadn't learned their lesson last season about keeping secrets, some characters are still keeping them -- like Caitlin.

Like Mother Like Daughter

Tonight Caitlin's mother, Dr. Tannhauser, made her debut on "The Flash." Caitlin went to see her mother after her powers began manifesting more intensely in last week's episode. A brilliant scientist like herself, Caitlin's mother was able to test Caitlin's powers in her cryogenics lab. While Caitlin was grateful for the lab help, she confessed to her mother that she was really there for emotional support. Ever since Earth-2 Killer Frost teased her "chilling" relationship with her mother back in season two, there's been speculation about what caused Caitlin and her mother to fall out. It turned out to come from the death of Caitlin's father. When he mother couldn't cope with that loss she threw herself into her work, effectively ignoring Caitlin and putting a vast distance between them. The two shared a tender moment tonight when Caitlin shared that she knew what it was like for her mother to lose her husband because she lost Ronnie too. While the coldness between them may have originally stemmed from this issue, it may now bond them, since they both have this loss in common.

Not [Yet] Killer Frost

Caitlin's powers manifested and gave her a slight alter ego when her mother's assistant, Nigel, tried to kidnap her. After locking Caitlin in the lab and threatening her life with harm, Caitlin grabbed his arm and began to freeze him. Her eyes began to glow and her voice even changed. Caitlin's mother was able to intervene by apologizing for not being there for her and by telling her that she wasn't a killer. The glow in Caitlin's eyes disappeared and she was back to herself. Based on this encounter, it looked like her powers were still based on emotion -- mainly anger and fear. At the end of the episode her mother warned her that if she kept using her powers, she would permanently become an ice-wielding metahuman. At what point will she tell her friends so they can help her use her powers for good?

HR Wells? More Like HG Wells

This episode also dealt with the newest member of Team Flash, Dr. HR Wells. Last week he apparently solved Earth-2 Harrison Wells' special test to screen for genius-level counterparts. While HR seemed to know his science and technology, it turned out that he was actually a writer and not the brainiac leader of Earth-19 S.T.A.R. Labs. This put Barry and Cisco in a tailspin, as it made the third time a leading member of their team had lied to them. This revelation meant that they did not get a genius-level Wells, but a storyteller, a man of ideas and not necessarily science. While the team was disappointed that he lied, they were relieved to know that he was not on their earth to harm them or disrupt their work, so they agreed to let him stay.

Not a Metahuman Expert After All

Everyone was full of surprises this week, including the CCPD's resident metahuman expert, Julian Albert. After weeks of butting heads and desks with Barry, Julian finally opened up about why he came to America to study metahumans. First, he shared that he actually didn't hate metas, but that he wished he was a meta, so he could use his powers for good. Second, after almost killing the kid who was controlling the hologram monster, Julian told Barry that he left England to start a new life on the force. Apparently, he wanted to shrug off the life of royalty and insignificance for an opportunity to do something that really mattered. This confession bonded Barry and Julian -- so much so that the pair even went out for a beer at the end of the episode.

Joe-isms & Emotional Grounding

Tonight's episode created space for a lot of deeply personal conversations between characters. Caitlin and her mom finally opened up to one another, Cisco and Wells came to a middle ground regarding his charade of being a scientist, and Barry and Julian finally saw each other through new eyes. While the heroic moments throughout the episode were fantastic and fun to watch, like Barry catching a bullet and saving Julian's life -- it was more impactful to see each character explore their feelings with such honesty. There were also some great shout-outs to "Star Wars" and Hitcock, as well as a peek into Barry and Cisco's new roommate situation. In the next episode of "The Flash," titled "Shade,"  Alchemy is back and Flashpoint will begin to awaken memories in Wally, who still doesn't know that he was a speedster in the other timeline.

Starring Gustin as the Scarlet Speedster, “The Flash” airs Tuesdays at 8 pm ET/PT on The CW. The series also stars Jesse L. Martin, Tom Cavanagh, Carlos Valdes, Candice Patton, Danielle Panabaker, Keiynan Lonsdale and more.