Warning: spoilers ahead for the Season 4 midseason finale of The Flash, called "Don't Run."
The Thinker has been messing with Barry and Team Flash throughout Season 4, but it was never clear what exactly he was planning. Between manipulating situations to create metahumans, sending samuroids after the local superheroes, and toying with the good guys in his civvies, the Thinker has caused plenty of trouble even without revealing what he had in mind. In fact, the only thing Team Flash really had going for them against the Thinker was the fact that the Thinker's body was degenerating at a dangerous pace and he was doomed to die sooner rather than later. His high-tech chair could only keep him alive for so long, and he was on his last legs. Team Flash could have theoretically waited him out.
That is, until the events of the midseason finale revealed that the Thinker has been working on a plan to restore himself all along, unbeknownst to Team Flash (and viewers). "Don't Run" revealed that the Thinker joined forces with another major villain to enact the next stage of the plan that would restore him to health and give him all the time in the world to plot against Barry and his pals in Central City. Yes, the Thinker teamed up with Amunet, as played by Katee Sackhoff. For the majority of the hour, it seemed that Amunet's plot with Caitlin was entirely separate from Barry's plot with the Thinker, who kidnapped him early on.
Amunet abducted Caitlin and forced her to restore another captured metahuman to health, and that metahuman was none other than Dominic Lanse, whose casting was announced recently. DC Comics fans know Dominic Lanse as the supervillain known as Brainstorm, which made it quite surprising when Dominic was introduced as a sympathetic character and ally to Caitlin. In fact, once Team Flash (sans Barry) seemed to defeat Amunet and rescue Caitlin and Dominic, Caitlin invited Dominic to the West Christmas party.
Meanwhile, Barry managed to escape from the Thinker, although not before embarking on a crazy chase throughout Central City. The Thinker zoomed through the air on his high-tech chair, with Barry hanging on for dear life on the back. That particular situation was resolved when both fell from very high in the air down into the water. Barry survived due to the life raft feature Cisco built into his suit, but the Thinker went straight down and didn't come up. They couldn't find a body, but there was no way he could have survived, right?
Well, yes and no. The final minutes of the episode revealed that the physical body of Clifford DeVoe was very much dead, but the mind of the Thinker lived on in the body of none other than Dominic Lanse. The big reveal happened when an alert at Barry and Iris' loft went off, prompting Barry to leave everybody at the Christmas party at the West house to check it out. Once there, he received a phone call from the person he believed was Dominic.
Dominic dropped the bombshell on Barry that he did not actually outthink the Thinker as he believed. Instead, with the help of Amunet, the Mechanic, and Dominic's own telepathic meta abilities, the Thinker was able to transfer his consciousness into a body that is healthy and whole. Now, a terrifyingly intelligent supervillain is in the body of a young man with telepathic powers with the Mechanic at his side. The only good news is that the Thinker didn't have any plans to hurt any of the people at the West house. His revenge on Barry was much more personal, and it made for a killer cliffhanger.
Sadly, we're going to have to wait until the new year to find out what happens next, as The Flash is now heading into its midseason break. We'll see more of the Thinker in Dominic's body moving forward, as actor Kendrick Sampson signed on for multiple episodes. Katee Sackhoff is set to recur in Season 4 as well. Basically, the good guys of Central City are in a lot of trouble, and we don't even know what the Thinker's "Enlightenment" plot is. All things considered, it should be fun to watch. Check out our midseason TV premiere schedule for when many shows will return to the airwaves in 2018.