Abstract: The fleet of spacecraft distributed in the inner heliosphere during May-June 2024 offered us the unique opportunity to analyze, over a wide range of heliolongitudes, the effects produced by the complex sunspot group formed by active region (AR) 13664. In early May 2024, AR 13664 started to produce a substantial number of M- and X- class solar flares and coronal mass ejections (CMEs) as it transited over the Earth’s visible side of the Sun. In particular, the arrival of these CMEs at Earth on May 10-11 produced major geospace disturbances.  As this complex AR formation rotated over the backside of the Sun, it continued producing X-ray flares and CMEs. At its return to Earth’s view (under the name of AR 13697) it kept producing multiple X-ray flares and CMEs. We combine remote-sensing observations from Solar Orbiter, STEREO-A, and near-Earth spacecraft (GOES, SOHO, SDO) to track the location and activity of this complex AR formation for two solar rotations. We analyze the intense solar energetic particle (SEP) events observed by these spacecraft from 2024 May 8 to 2024 Jun 21. Energetic particle data collected by near-Earth spacecraft and by Solar Orbiter (separated by ~170 degrees in longitude) displayed multiple particle intensity enhancements associated with individual SEP injections and with the arrival of shocks driven by CMEs. The result of all this activity included a long-time interval (>40 days) with elevated (>10 MeV) proton intensities observed at well separated heliolongitudes. The most intense >10 MeV proton intensity enhancement measured by Solar Orbiter during this period was associated with a backside (as seen from Earth) fast halo CME (with an estimated speed of ~2000 km/s) that occurred on May 20 together with an intense X-ray flare (with an estimated X16 GOES class flare). This SEP event resulted in a long-lasting period of elevated SEP intensities with the peculiarity of a hard energy spectrum observed by near-Earth spacecraft.