A young woman named Ellen visits her aunt's huge mansion to recuperate after a stay in a mental institution. Here she encounters noises in the night, figures loitering in the dark and doors that lock and unlock by themselves.
For a change this turns out to be more of a heist caper than the usual inheritance grab. It's also enlivened by characters other than just the heroine having sections where their thoughts and motivations are depicted. This made for a better read. However the insistence on characters telling Ellen thats she's hysterical and "seeing things" is as irritating as ever. So is giving Ellen the predictable choice of two equally handsome men for her to twitter on about. A bit of advice for gothic heroines: when one potential suitor is suave and almost too charming, and the other disappears a lot and seems to hold a secret, you should always choose the one holding the secret. The "Moon Garden" of the title adds a little spot of diversion but it's just window dressing to the plot.