Memento (Warning) is a young adult novel with reporting elements, written by Czech author Radek John and published in 1986.

It was made into a film for Czechoslovakian television in 1990 [1] The novel is written with literary language with elements of argot and slang of drug addicts.

Its importance lies in the fact it is the first work concerning this taboo theme in the time of the previous totalitarian communist regime in Czechoslovakia.

Michal tries to live in a shared flat with Eva, but drugs permeate their relationship and they cannot tolerate each other's company without it.

There are repeated attempts to go 'cold turkey,' but always either Michal or Eva relapse and trapped in co-dependency, they both become mired within the addict subculture once more.

Eva becomes pregnant again and Michal learns that she was poisoned by anhydrous ammonia (used in the manufacture of crystal meth) during that pregnancy.

Michal is suffering from a severe stomach ulcer due to his crystal meth addiction so he initially disbelieves that Eva has committed suicide.

Suffering from narcotic psychosis, he believes that Eva was murdered by someone from the initial addict network in Prague, which is now trying to kill Michal as well.

After his latest period in prison, Michal and several neophyte addicts, prepare to avenge themselves against the network.

After he is released from the hospital, Michal continues to take drugs and after another overdose he is found by his mother in a comatose condition.