Stair-step cracks follow the mortar joints diagonally and usually signal differential settlement (one part of the foundation dropping) or lateral movement. Cracks wider at the top point to settlement; cracks on a basement wall running toward the corners point to a wall being pushed in. Both warrant an engineer.
More detail
A stair-step crack zig-zags along the mortar joints of brick or block because mortar is the weakest plane, so when the masonry is stressed the crack follows the path of least resistance through the joints. The direction and shape tell you what is happening. On an exterior brick veneer or a foundation wall, a stair-step crack that is wider at the top than the bottom typically means differential settlement: one section of the footing has dropped relative to the rest, opening the wall up like a hinge. A stair-step crack wider at the bottom can indicate heave (that section pushing up) or a different settlement pattern. On a basement block wall, stair-step cracks running diagonally toward the corners, often combined with a horizontal crack across the middle, signal lateral soil pressure pushing the wall inward. The cause determines the fix entirely: settlement is corrected by underpinning the dropped section with piers to carry the load to stable strata, while lateral movement is corrected by stabilizing the wall with carbon fiber, beams, or anchors and relieving the soil-and-water pressure behind it. Because the two require completely different repairs, and because the soil mechanics in Cincinnati's clay and hillside conditions can be subtle, we bring in a licensed engineer to read the crack pattern, measure the movement, and diagnose the cause before proposing anything. A contractor who quotes a fix off a photo of a stair-step crack without measuring and without an engineer is guessing.