The Flash, Arrow and Legends of Tomorrow - 'Invasion!'

Believe it or not, this is not a good thing.

So, there was 'Medusa', and now we begin the real-deal; the mega-crossover of the four CW DC shows with episodes of The Flash, Arrow and Legends of Tomorrow all entitled 'Invasion!'(1)

Barry's contemplation of unemployment is interrupted when a space ship crash lands in the park during HR's 'STAR Labs Museum' presentation and a bunch of super-strong aliens known to Lila as 'Dominators' go rushing off into the shadows. Lacking experience in this field, Barry recruits help. First Oliver, John and Thea - the latter coming out of retirement, because aliens, right - from Star City, then Sara, Stein, Jax, Ray and Mick from the Legends, leaving Nate and Amaya to mind the Waverider. Finally, with help from the recalcitrant Cisco, he breaches the dimensional barrier and brings Kara across from Earth-38. Meanwhile, the President is kidnapped by aliens and a mysterious and very senior agent tells Lila she ought not to cross him by trying to deal with the situation.

Bloody aliens and their mind control. It's like X-COM all over again.

The team quickly runs into trouble when Oliver nominates Barry for project lead, but has to prompt him on just about everything, which at least prevents Barry from formulating any plans. Oliver suggests that they train against Supergirl. He asks her not to hold back and she doesn't, basically trouncing everyone in short order, because Supergirl.

Then Stein and Jax share the recording of future Barry, which it turns out warns them not to trust current Barry on account of his Flashpoint shenanigans. They agree to keep it secret until after the crisis, but Cisco spills the beans because he's understandably pissed that people just keep on giving Barry a break when he screws up. Learning that his attempt to save his family killed Cisco's brother, disappeared Sara Diggle(2) and all sorts, everyone except Oliver, who arguably has something of a vested interest in promoting a forgiving attitude to major fuckups, decides they don't want to work with him, instead going in without Barry or Oliver, which results in badness. The team have no real cohesion, Mick insists on calling Kara 'Skirt', the President gets vaporised and the team all get mind controlled into attacking the supergroup's temporary HQ.

Fortunately, Oliver is able to hold off the others while Barry goads Kara into chasing him and inadvertently blasting the mind control device. Unfortunately, POTUS is still in the wind, as it were(3), and moreover John, Sara, Ray, Thea and Diggle are almost immediately teleported away to who know's where.

Uh-huh.

Well, 'where' turns out to be a blissful, sun-drenched Starling City, where Oliver is about to marry Laurel Lance and take a job at Queen Consolidated, Thea is a successful nightclub owner, Sara is back in town for the wedding, Ray Palmer is engaged to Felicity Smoak, who moonlights as the assistant to the vigilante known as the Hood, aka John Diggle. Malcolm Merlyn is a good family friend, although sadly Tommy couldn't get away from his work as a doctor in Chicago(4).

Did we mention this is also their 100th episode of Arrow?

Gradually, the captives all become aware that something is wrong with their world and remember reality. Meanwhile, Felicity brings in Barry, Kara and Cisco to assist NTA in locating the missing team members. They take down a doctor with tech-based electrical powers to retrieve a component - and give Kara and Barry a chance to prove to Wild Dog that they aren't just fronting on being heroes - in order to link to a piece of alien machinery and find their friends... in outer space.

Well, there's something you don't see every day.

The captives, with varying degrees of reluctance - Thea in particular is very tempted to remain - decide to break out through the one incongruous structure in the city; the Smoak Technologies tower. They fight their way past basically every major villain they could get back for a cameo and escape into the alien ship, then into a shuttle, and are finally rescued by the Waverider.

Back at home, Stein also realises that the young woman he has been remembering since interacting with his younger self, the one that he is certain that he loves, is not some trophy wife; she is his daughter. This is pretty traumatic for him, since he never had children before. The problem is compounded when Stein begins working on a nanotech solution to the invasion and Caitlin naturally brings in Lily Stein to help, since she's a brilliant nanotechnologist (and happens to share a lot of Caitlin's style.)

Abomination!

Moving up into the finale, Mick, Nate and Amaya take Cisco and Felicity back in time to kidnap a Dominator from the first encounter where a small force of the aliens wiped out an army unit in Oregon in 1951. They themselves quickly get abducted, however, when a creepy government agent bags them and the alien and begins torturing the Dominator. Felicity and Cisco break the team out and they rescue the Dominator, unwilling to allow anything to be tortured. In thanks, the same Dominator in 2016 tells Cisco that they are here for Barry. They see metas as a threat, and Barry's temporal shenanigans are more than they can overlook. Therefore they are going to wipe out the metahuman population with a special bomb that is... kind of selective, but not very.

The creepy senior agent - who is creepy goverment agent from 1951 all growed up - insists that Earth will keep to its treaty with the Dominators whatever happens, but as Stein allows himself to bond with Lily, they create a device that will cause intense pain to a Dominator. In a final showdown, the team fight the invaders while Supergirl - to whom Oliver was earlier a complete dick - and Barry slap devices on all the Dominators on the planet, while Firestorm transmutes the meta-bomb into water. The Dominators bug out and its home for medals and champagne (literally; the new President attends the celebration to hand out secret gongs and creepy agent is sent off to Alaska.) Kara is given a dimension-hopper and everyone goes home.

This is a top-ten answer to the question 'you and whose army?'

'Invasion!' is a hell of a thing. It's not as joyous as 'World's Finest', because virtually nothing is, but it's a pretty solid, if atypical, adventure. By modifying the team in each show they make sure that everyone does something and the screen is never over full. By changing the pace for a slower second act, it keeps the action and drama from outstaying its welcome. It mixes and matches the teams well, with the only real false note being Oliver's sudden dickishness to move Kara out of the middle act of Legends of Tomorrow. The crossover also serves to restore people's faith in Barry; even Cisco, who realises that with the best will in the world, he changed things when he went back in time. I'm not ready to forgive him for Sara, however, and if Stein is later forced to go through with his original plan of erasing Lily from the world, I'm going to cut a fool. Figuratively speaking.

And yes, Kara is OP. Of course she's OP; she's Supergirl.

(1) Yes; with the exclamation mark.
(2) I'm not letting this one go either.
(3) Because he's a vapour. Too soon?
(4) Ah; actor's new job humour.