Definitions of involved:

• adjective:   connected by participation or association or use

  Example: "We accomplished nothing, simply because of the large number of people involved"

• adjective:   enveloped

  Example: "A castle involved in mist"

• adjective:   emotionally involved
• adjective:   entangled or hindered as if e.g. in mire

  Example: "The difficulties in which the question is involved"

• adjective:   highly involved or intricate

  Example: "The plot was too involved"