This time around, Anthony Mackie is taking over the lead role of Takeshi Kovacs from Joel Kinnaman. Since Altered Carbon is set in a future in which people can transfer their consciousness and memories between bodies (or "sleeves"), recasting parts isn't too complex.
There's no trailer as yet for the second season, but Netflix has offered some details of what's in store. Kovacs will continue his galaxy-spanning, centuries-long search for his lost love, Quellcrist Falconer, while trying to get to the bottom of a string of murders. However, it seems that both of his missions are connected.