The Devil's Discus is an investigation into the death of King Ananda Mahidol (Rama VIII) of Siam (later Thailand) by English-South African author Rayne Kruger.

He supports this theory with the revelation of a love affair between the young King and a fellow law student in Switzerland, Marylene Ferrari, a relationship which would not have been acceptable to Siam's royalist institutions.

[4] In 2016, the Supreme Court of Thailand ruled that selling this book constituted an offence of lèse-majesté under section 112 of the Thai Penal Code and sentenced a 67-year-old man to two-year imprisonment on account thereof.

The Devil’s Discus was envisaged as a way of rehabilitating Pridi’s reputation in the hope that he would be able to return from exile and play a leading role in Thai politics once again."

And to conclude that Bhumibol was responsible was, of course, totally unacceptable to the royalist establishment – the book was supposed to enable détente between Rama IX and Pridi, not to declare full-scale war.