The City of Shifting Waters (La Cité des eaux mouvantes) by the French creative team of author Pierre Christin & artist Jean-Claude Mézières is the vintage 1st album in their long-running Valérian et Laureline bande dessinée series of science fiction time travel adventure comics, free for a limited time in both languages courtesy of publisher Dargaud’s Cinebook imprint.
This was originally published way back in 1970 and is the start of one of the major classic Franco-Belgian comic book series, which is being made free to promote an upcoming film adaptation. The series stars spatio-temporal agents from a 28th century Terran Empire who protect the past. This adventure sends them back in time to New York City in 1986 (as envisioned in 1970), in order to thwart a rogue time traveler who seems to have already changed the future.
Offered in selected countries worldwide (mostly North America & Europe) in both the original French and an English-language translation, available at multiple retailers.
The English-language translation The City of Shifting Waters is available in selected regions @ Amazon, Kobo[kb], iTunes[it], [Google Play][gp], Comixology (this was free in Canada, the US, UK, and various European countries when I spot-checked, YMMV; not all retailers carry the freebie in all countries, so it’s probably worth changing the country codes in the URL or trying a different store to see if it’s free for your locale)
Galaxity, capital of the Terran Empire in the 28th century. Valerian and Laureline are agents who protect mankind from rogue time travellers. Now they are sent to New York in 1986 to intercept Galaxity’s worst megalomaniac, Xombul—except that in 1986, the world is in ruins and New York is about to be swallowed by the ocean. The two agents must navigate the shifting waters of the past to make sure that the future will exist.