Out of all the holidays and events in Overwatch, the annual Archives events are by far the most interesting. They bring with them a variety of co-op missions to test your skills against, a deeper dive into the history of the Overwatch organization itself, and naturally, a whole bunch of themed skins to mess around with. The upcoming Overwatch: Storm Rising event will be no different.
It'll offer you a chance to play through all of the previous Archives missions, as well as explore a brand new mission where Tracer, Genji, Winston and Mercy will be hunting down Maximillien, a Talon Omnic, through the streets of Havana. The details are currently few and far between, but given the previous two Archives events, the new co-op mission should be a good bit of fun!
On a similar note, it's also likely we'll be getting a fully fledged Havana map in the near future, much like how we got Rialto after the previous Archives event. As for what exactly the map will be about, that I can only speculate on, but I'd say chances are good that Havana will be an escort map (like King's Row) given that the co-op mission will be a chase, and as such require a rather long stretch of map for the team to explore.
Whether I'm correct or not, I suppose we'll see soon enough as the Overwatch: Storm Rising event will be running from April 16 - May 6. You can read a little bit more about it, as well as follow any further teasers, over at the official website.