Spin ladders present a class of low-dimensional quantum magnets that occupy a regime of rather subtle behavior which lies between the stark extremes of a one-dimensional chain or two-dimensional plane. The molecular magnet (C_{7}H_{10}N){2}CuBr{4}, known as DIMPY, is a recently discovered compound in which CuBr_{4}^{2-} groups form two-leg spin ladders. Specific heat measurements reveal the presence of a spin Luttinger liquid phase above a critical field 3.0(3) T: a field which is accessible with the new HiFi spectrometer at ISIS! The discovery of this material gives us the first opportunity to probe the quantum phase transition in a spin ladder system with implanted muons. We propose to make longitudinal-field muSR measurements on a high quality single crystal sample of DIMPY using the HiFi.