The Case of Charles dexter Ward -which remained unpublished during H. P. L. 's lifetime- is certainly one of the most readable and enjoyable efforts of the old gentleman from Providence, even for people who are not addicted to "Call of Cthulhu" role-playing games and similar items about which Grandpa Theobald would probably have been both rather amused and irritated.
The story, unfolding slowly but with an ever increasing pace, revolves around the uncanny relation between one Charles Dexter Ward -a young antiquarian of an old Providence family, quite an alter ego of Lovecraft himself- and his ancestor Joseph Curwen, a Salem warlock from the 17th century. The descriptions of old Providence and its surroundings are exceedingly beautiful and graphic and reveal much of H. P. L. 's affection for his hometown. The story, of course, also has its great moments of cosmic fear, and the accounts of the good people of Providence's raid against Joseph Curwen and that of Dr. Willett, the avuncular and benevolent medical doctor of Ward's family, descending into the sheer abyss of horror (without even a drop of blood being splattered) belong to the most frightening and effective episodes in all of horror literature.
Lovecraft delves deeply into occult lore and black magic, much more so than in most of his other stories, where he mainly relies on some name-dropping, usually of the Great Old Ones and his own invented grimoires (like the Necronomicon & Cie.) to provide a touch of witchcraft, but he does it with utmost effectiveness, in total contrast to many of his contemporaries (and successors). The reason for this is certainly that he was a complete non-believer concerning anything supernatural.
The way the ever increasing atmosphere of threat and madness is built up is masterful, even though the end of the story is not really a surprise for an intelligent reader (especially anyone used to Lovecraft's work, which almost never offers that kind of thrill, "The shadow over Innsmouth" being probably the only noteworthy exception). Nevertheless he manages to keep a tantalizing amount of uncertainty for quite a while, much more so than, e. g., in the much-admired "The shadow out of time".
The so-called Cthulhu Mythos plays only a very minor role in "The Case". To give an example -for those cthulhuoid guys out there- I fully agree with S. T. Joshi who once admitted that he never could really figure out what Yog-Sothoth exactly meant in this novel (does anybody know what it really meant in any H. P. L. story, by the way ? I don't talk about August Derleth's and Lin Carter's kids and grannies versions of the Mythos, which have become so well-liked by most of the would-be Lovecraftians. Except for Cthulhu himself, H. P. L. always kept a veil over the deities of his pantheon).
The novel offers everything you can excpect from the undoubted master of the macabre in the 20th century, suspense, chills & thrills and all-out horror, but in a subtler and more convincing way than in most of his earlier and some of his later works. A recommendable book for everybody interested in good, well-(love)crafted horror stories, and certainly not only of historical interest.