complex

Holmes himself had said that no more complex case had come to him in all the long series of his sensational investigations.

This case of yours is very complex, Sir Henry.

For my own part, I had followed step by step the methods by which he had traced the various windings of this complex case, and, though I could not yet perceive the goal which we would reach, I understood clearly that Holmes expected this grotesque criminal to make an attempt upon the two remaining busts, one of which, I remembered, was at Chiswick.

It's worth our attention, for, granting that the man is a rascal, he is certainly a complex and ingenious one.