  We introduce a systematic approach to constructing $\mathcal{N}=1$
Lagrangians for a class of interacting $\mathcal{N}=2$ SCFTs. We analyse in
detail the simplest case of the construction, arising from placing branes at an
orientifolded $\mathbb{C}^2/\mathbb{Z}_2$ singularity. In this way we obtain
Lagrangian descriptions for all the $R_{2,k}$ theories. The rank one theories
in this class are the $E_6$ Minahan-Nemeschansky theory and the $C_2\times
U(1)$ Argyres-Wittig theory. The Lagrangians that arise from our brane
construction manifestly exhibit either the entire expected flavour symmetry
group of the SCFT (for even $k$) or a full-rank subgroup thereof (for odd $k$),
so we can compute the full superconformal index of the $\mathcal{N}=2$ SCFTs,
and also systematically identify the Higgsings associated to partial closing of
punctures.
