Castle Bravo is a 32-page adventure for the Trail of Cthulhu RPG, written by Bill White and published by Pelgrane Press. It is available only in pdf format, and is priced at a very reasonable $5.95. While it has an attractive color cover, the interior is black & white making it very printer-friendly. In terms of appearance, the adventure is attractively laid out, with excellent, evocative artwork inside and everything you need to run the adventure, including six pregenerated characters.
The adventure is designed for 3-6 players with the "sweet spot", according to the author, being four players. The adventure itself plays out aboard a US Navy aircraft carrier on a nuclear test mission in the Bikini Atoll in 1954. To keep this as spoiler-free as possible, let's just say that the previous atomic detonations drew the attention from something beyond and this follow-up test won't go as smoothly as those in command planned. The adventure is written specifically to be run in Purist-mode for Trail of Cthulhu, although it could easily be adapted to use as a pulp-style adventure as well and the nature of the adventure works equally with either style of play.
One of my favorite parts of the adventure is the waythe aircraft carrier - on which much of the adventure takes place - is handled: rather than trying to provide exhaustive maps of a very labyrinthine craft, the author has broken the ship into a set of zones, creating a simplified schematic that can be used to see how the zones relate to one another and thus how the characters might navigate the ship. This fits very well with ToC's low-overhead GM style and keeps things focused on the action and story rather bogging down in to a square-by-square dungeon crawl.
Pelgrane Press has put out a lot of great Trail of Cthulhu adventures and Castle Bravo is one of their best because it pays homage to HPL's stories while at the same time presenting an original setting in which they unfold. I can't recommend it enough. However, one minor issue with Castle Bravo's premise and set-up needs to be mentioned as a "buyer be aware" piece of info: the adventure takes place in 1954 and thus is outside the normal time frame of the default ToC era. It also is based on the assumption that the characters are members of the military - given the top-secret nature of the mission civilian involvement seems fairly implausible in most cases - and ideally the adventure really runs best as a one-shot, ideally using the pregenerated characters provided. Therefore, fitting the adventure into an ongoing ToC campaign would be difficult for most groups and is something anyone looking for the next adventure in their ongoing campaign needs to be aware of before purchasing the adventure - the use of the Bikini Atoll atomic tests as a premise for the adventure means that moving the adventure forward or backward in time would be difficult. In reality, this shouldn't discourage most people considering purchasing the adventure since as a "purist" adventure, characters aren't really meant to finish the adventure unscathed and so I think Castle Bravo is ideal for a one-shot game lasting 1-3 sessions. Therefore, I would still rate the adventure as a "should buy" for anyone who is a fan of Trail of Cthulhu.