Michael Mann is planning another film on the Russian Agent that died from poisoning, Alexander Litvinenko. The first film was announced under Johnny Depp's production company just recently.

This one is going to be from another book called Death of a Dissident which is being written by the widow of the man, Marina Litvinenko and Alex Goldfarb. This book isn't so much about the man and his life but according to Variety through Empire is much more political than that:

...on the Russian power structure enforced by the KGB and its successor the FRS, and the "Wild West capitalism" (think Deadwood) that followed glasnost, with Litvinenko caught between those two colossal forces.

There's no word yet about matching release schedules or on the other novels due out on the same agent and topic. It does look like it's going to be a crowded marketplace for this story though.