Hellebores are not the best choice for dense shade - they are shade tolerant, not necessarily shade lovers. While many will grow in rather heavy shade, blooming will be sparse. What exactly do you mean by "dense" shade? Unless under an low overhang or the heavy canopy of a larger plant or tree, adjacent to a wall is typically part shade to indirect light.

Something to consider: I planted my helibores underneath several trees, while shady to a point, when they bloom in spring, the foliage in the trees has not yet opened...so really, while it is still cool, the plants are in full sun....only later in the season are they shaded...when they would rather not deal with the sun/heat.

Cheers,
M