In general, an undisclosed principal and the third party to a contract are contractually bound if the agent acts within the scope of his actual authority in making the contract.

Undisclosed Principal

A situation in a business transaction where the identity of the principal (the person for whom the agent acts) is not revealed to the third party involved in the deal.

Actual Authority

The explicit power granted to an agent by a principal, allowing the agent to act on the principal's behalf.

Scope

The extent or range of view, work, or activity; the breadth of a project or operation.