Sorry, but could you re-post the question with more particulars? Or you could join GoY for free, and we could discuss it more freely.

Welcome, Eurodoyle!
Is that a Hibiscus syriacus or a different kind? Did it leaf out in late spring, only to lose its leaves later? And did you water it during the drought?

one of mine has shed its leaves as I forgot where it was and it got too dry. it is re leafing now that i have started to keep it watered :o)