An interaction caused by a stopping heavy meson has been observed in emulsion. One of the four particles emitted in the interaction is interpreted as a nuclear fragment with a Λ0 attached. The subsequent mesonic decay of this bound Λ0 leads to a Q of 34.2+/-0.9 Mev. The measured mass of the heavy meson is 1010+/-200me. The visible kinetic energy released in the interaction it causes is 50+/-8 Mev.