Indirect, circuitous, roundabout are comparable when applied to ways, routes, or means with the meaning not leading by a straight path to a destination or goal.
Indirect basically implies departure from the straight and short line between two points. In its extended uses indirect implies following a course that is not plain, obvious, explicit, or straightforward.
Circuitous implies not only indirection but usually a winding and, because of its length, slow way or course.
Roundabout may be used interchangeably with circuitous, but specifically it implies a following of a more or less circular or semicircular course from one point to another; the term more often than indirect or circuitous, especially in its extended use, implies deliberate, often blameworthy evasion or avoidance of the direct course or way.