The Operation Phoenix Trilogy is a three part mini series in the Casefiles series, that ran from June 1992 until August 1992. Like the rest of the Casefiles, it was produced by Mega-Books and published by Simon & Schuster's Archway Paperback imprint.
The three titles in the trilogy, Endangered Species, No Mercy, The Phoenix Equation, are also books #64, #65, and #66 in the main Casefiles series.
The A Hardy Boys And Tom Swift Ultra Thriller novel Time Bomb is considered to be an epilogue to this trilogy since the events of that novel take place within a matter of weeks of this trilogy, and this trilogy is mentioned in the book.
Plot summary
The Hardy boys join their father, Fenton on an undercover mission in Africa, to investigate a multimillion dollar smuggling ring, and discover the fate of a missing U.S. Customs official who was on the trail of the gang before he disappeared.
The poachers are killing hundreds of endangered animals, for their smuggling operation, and the Hardys determined to shut them down.
Frank and Joe discover that the Customs official was killed, and are closing in on the gang, when their own father is killed in a tragic bombing. Following a clue, the brothers leave Africa and head to Stockholm, Sweden on the trail of their father's killers.