The Street of One Thousand Eyes (Hong Lei Chung #2), by Harry Stephen and Hazel Goodwin Keeler (epub/Kindle/pdf)

Joseph Fairweather languishes in a mental institution because he has a theory about time and space that’s just plain crazy. Across the ocean in an abandoned warehouse by the River Thames, Eadgyth Whit­church lies bound hand and foot, soon to be thrown into the river by the London branch of the Tong of the Lean Grey Rats That Swarm the World, just because she overheard a phone conversation she shouldn’t have. Meanwhile, back in the States there’s a slab of ancient stone that seems to disappear and reappear according to some laws of nature we know nothing about. What’s going on here?