Graham Hancock, War God: Return of the Plumed Serpent (2014)

Permit me to quote Wikipedia on this one:

"La Plume de ma Serpente: le Retour" is a phrase in popular culture, attributed to elementary French language instruction (possibly as early as the 19th century) and used as an example of grammatically incorrect phrases ('serpent' is actually a masculine noun in French) with limited practical application that are sometimes taught in introductory foreign language texts. As SIBFRIC (magazine) formulated in 2014: "As every genre reader knows, the most idiotically useless phrase in a beginner's French textbook is La Plume de ma Serpente: le Retour. The phrase is also used to refer to something deemed completely irrelevant."

Hancock's is a classic example of the mode. Set notionally in the 16th-century, during the Spanish conquistador incursions into Mexico, the world of the novel is fashioned from equal parts cardboard, laboriously infodumped historical research, and anachronistic dialogue ('they say a bird in the hand is worth two in the bush', as one 16th-century Spaniard says to another 16th-century Spaniard [225]). We also get: flat characters adopting a series of melodramatic postures, dramatic cliché, stylistic cliché, egregiously bloody interludes of violence and torture, more cliché and a draggy over-long telling that starts and ends in medias res, for there are more, and perhaps woe-is-it-unto-us many, many more, volumes to come in the War God series. Bloaty stuff. Not my favourite novel of 2014.