  On 2020 April 19 a coronal mass ejection (CME) was detected in situ by Solar
Orbiter at a heliocentric distance of about 0.8 AU. The CME was later observed
in situ on April 20th by the Wind and BepiColombo spacecraft whilst BepiColombo
was located very close to Earth. This CME presents a good opportunity for a
triple radial alignment study, as the spacecraft were separated by less than
5$^\circ$ in longitude. The source of the CME, which was launched on April
15th, was an almost entirely isolated streamer blowout. STEREO-A observed the
event remotely from -75.1$^\circ$ longitude, which is an exceptionally well
suited viewpoint for heliospheric imaging of an Earth directed CME. The
configuration of the four spacecraft has provided an exceptionally clean link
between remote imaging and in situ observations of the CME. We have used the in
situ observations of the CME at Solar Orbiter, Wind, and BepiColombo, and the
remote observations of the CME at STEREO-A in combination with flux rope models
to determine the global shape of the CME and its evolution as it propagated
through the inner heliosphere. A clear flattening of the CME cross-section has
been observed by STEREO-A, and further confirmed by comparing profiles of the
flux rope models to the in situ data, where the distorted flux rope
cross-section qualitatively agrees most with in situ observations of the
magnetic field at Solar Orbiter. Comparing in situ observations of the magnetic
field between spacecraft, we find that the dependence of the maximum (mean)
magnetic field strength decreases with heliocentric distance as $r^{-1.24 \pm
0.50}$ ($r^{-1.12 \pm 0.14}$), in disagreement with previous studies. Further
assessment of the axial and poloidal magnetic field strength dependencies
suggests that the expansion of the CME is likely neither self-similar nor
cylindrically symmetric.
